diff --git a/app/models/exports/pdf/common/attachments.rb b/app/models/exports/pdf/common/attachments.rb
index 3816fa3b5a9..adeae6a9958 100644
--- a/app/models/exports/pdf/common/attachments.rb
+++ b/app/models/exports/pdf/common/attachments.rb
@@ -66,8 +66,12 @@ module Exports::PDF::Common::Attachments
     return nil if local_file.nil?
 
     filename = local_file.path
-    filename = convert_gif_to_png(filename) if attachment.content_type == "image/gif"
-    filename = convert_webp_to_png(filename) if attachment.content_type == "image/webp"
+    if attachment.content_type == "image/gif"
+      filename = convert_gif_to_png(filename)
+    elsif attachment.content_type == "image/webp"
+      filename = convert_webp_to_png(filename)
+    end
+    return nil if filename.nil?
 
     resize_image(filename)
   end
@@ -90,12 +94,58 @@ module Exports::PDF::Common::Attachments
   def convert_webp_to_png(filename)
     tmp_file = temp_image_file(".png")
 
-    image = MiniMagick::Image.open(filename)
-    image.format("png")
-    image.write(tmp_file)
+    # ImageMagick loads ALL frames of an animated WebP into its pixel cache even
+    # when only frame 0 is needed, which can exhaust memory or even cache for large animations.
+    # Instead, parse the RIFF/WEBP binary to extract the first ANMF frame as a
+    # standalone single-frame WebP, then convert only that.
+    source = extract_first_webp_frame(filename) || filename
+
+    image = MiniMagick::Image.open(source)
+    image.frames.first.write(tmp_file)
     tmp_file
   end
 
+  # Parses the RIFF/WEBP container and extracts the first animation frame
+  # (ANMF chunk) as a standalone single-frame WebP written to a temp file.
+  # Returns nil if the file is not an animated WebP.
+  #
+  # Each ANMF frame in animated WebP is independently encoded (no inter-frame
+  # references), so the raw frame chunk is a valid standalone WebP image.
+  def extract_first_webp_frame(filename) # rubocop:disable Metrics/AbcSize, Metrics/PerceivedComplexity
+    data = File.binread(filename)
+    return nil unless data.bytesize > 12 && data[0, 4] == "RIFF".b && data[8, 4] == "WEBP".b
+
+    webp_type = %W[VP8\x20 VP8L VP8X]
+    pos = 12
+    while pos + 8 <= data.bytesize
+      chunk_id = data[pos, 4]
+      chunk_size = data[pos + 4, 4].unpack1("V")
+      break if pos + 8 + chunk_size > data.bytesize
+
+      if chunk_id == "ANMF".b && chunk_size > 16
+        # ANMF payload: 16 bytes of frame metadata (position, size, duration, flags)
+        # followed by the frame image data as a VP8 / VP8L / VP8X chunk.
+        # Wrap it in a minimal RIFF/WEBP container to create a single-frame WebP.
+        frame_chunk = data[pos + 8 + 16, chunk_size - 16]
+        # Reject frames whose payload isn't a recognised WebP bitstream type
+        next unless webp_type.map(&:b).include?(frame_chunk[0, 4])
+
+        riff_size = 4 + frame_chunk.bytesize # "WEBP" + frame data
+        tmp_frame = temp_image_file(".webp")
+        File.binwrite(tmp_frame, "RIFF".b + [riff_size].pack("V") + "WEBP".b + frame_chunk)
+        return tmp_frame
+      end
+
+      # RIFF chunks are padded to even byte offsets; use & 1 to get the padding.
+      pos += 8 + chunk_size + (chunk_size & 1)
+    end
+
+    nil
+  rescue StandardError => e
+    Rails.logger.error "Failed to extract first webp frame: #{e}"
+    nil
+  end
+
   def attachment_by_api_content_src(src)
     return nil if src.empty?
 
diff --git a/spec/fixtures/files/animated.webp b/spec/fixtures/files/animated.webp
new file mode 100644
index 00000000000..36cf1e75048
Binary files /dev/null and b/spec/fixtures/files/animated.webp differ
diff --git a/spec/models/exports/pdf/common/attachments_spec.rb b/spec/models/exports/pdf/common/attachments_spec.rb
new file mode 100644
index 00000000000..d0358719c4d
--- /dev/null
+++ b/spec/models/exports/pdf/common/attachments_spec.rb
@@ -0,0 +1,443 @@
+# frozen_string_literal: true
+
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require "spec_helper"
+
+RSpec.describe Exports::PDF::Common::Attachments do
+  let(:helper) do
+    obj = Object.new
+    obj.extend(described_class)
+    # api_url_helpers is defined in Exports::PDF::Common::Common, not in
+    # Attachments. Provide a minimal implementation so the module methods work.
+    obj.define_singleton_method(:api_url_helpers) { API::V3::Utilities::PathHelper::ApiV3Path }
+    obj
+  end
+
+  describe "#pdf_embeddable?" do
+    %w[image/jpeg image/png image/gif image/webp].each do |type|
+      it "returns true for #{type}" do
+        expect(helper.pdf_embeddable?(type)).to be true
+      end
+    end
+
+    %w[application/pdf text/plain image/svg+xml application/binary].each do |type|
+      it "returns false for #{type}" do
+        expect(helper.pdf_embeddable?(type)).to be false
+      end
+    end
+  end
+
+  describe "#temp_image_file" do
+    after { helper.delete_all_resized_images }
+
+    it "returns a string path ending with the given extension" do
+      path = helper.temp_image_file(".png")
+      expect(path).to end_with(".png")
+    end
+
+    it "registers the temp file so delete_all_resized_images can clean it up" do
+      helper.temp_image_file(".png")
+      expect { helper.delete_all_resized_images }.not_to raise_error
+    end
+
+    it "accumulates multiple temp files" do
+      helper.temp_image_file(".png")
+      helper.temp_image_file(".jpg")
+      expect { helper.delete_all_resized_images }.not_to raise_error
+    end
+  end
+
+  describe "#delete_all_resized_images" do
+    it "does not raise when no images have been created yet" do
+      expect { helper.delete_all_resized_images }.not_to raise_error
+    end
+
+    it "calls close! on each registered temp file" do
+      tmp1 = instance_double(Tempfile)
+      tmp2 = instance_double(Tempfile)
+      allow(tmp1).to receive(:close!)
+      allow(tmp2).to receive(:close!)
+
+      helper.instance_variable_set(:@resized_images, [tmp1, tmp2])
+      helper.delete_all_resized_images
+
+      expect(tmp1).to have_received(:close!)
+      expect(tmp2).to have_received(:close!)
+    end
+
+    it "resets the list to an empty array" do
+      tmp = instance_double(Tempfile)
+      allow(tmp).to receive(:close!)
+      helper.instance_variable_set(:@resized_images, [tmp])
+      helper.delete_all_resized_images
+      expect(helper.instance_variable_get(:@resized_images)).to eq([])
+    end
+  end
+
+  describe "#resize_image" do
+    let(:png_fixture) { Rails.root.join("spec/fixtures/files/image.png").to_s }
+
+    after { helper.delete_all_resized_images }
+
+    it "returns a path string" do
+      result = helper.resize_image(png_fixture)
+      expect(result).to be_a(String)
+    end
+
+    it "writes the resized image to the returned path" do
+      result = helper.resize_image(png_fixture)
+      expect(File.exist?(result)).to be true
+      expect(File.size(result)).to be > 0
+    end
+
+    it "writes a file with image/png MIME type" do
+      result = helper.resize_image(png_fixture)
+      expect(Marcel::MimeType.for(Pathname.new(result))).to eq("image/png")
+    end
+  end
+
+  describe "#convert_gif_to_png" do
+    # Use the PNG fixture as a stand-in; MiniMagick handles it fine.
+    let(:source_fixture) { Rails.root.join("spec/fixtures/files/image.png").to_s }
+
+    after { helper.delete_all_resized_images }
+
+    it "returns a path ending with .png" do
+      result = helper.convert_gif_to_png(source_fixture)
+      expect(result).to end_with(".png")
+    end
+
+    it "writes a non-empty file to the returned path" do
+      result = helper.convert_gif_to_png(source_fixture)
+      expect(File.exist?(result)).to be true
+      expect(File.size(result)).to be > 0
+    end
+
+    it "writes a file with image/png MIME type" do
+      result = helper.convert_gif_to_png(source_fixture)
+      expect(Marcel::MimeType.for(Pathname.new(result))).to eq("image/png")
+    end
+  end
+
+  describe "#convert_webp_to_png" do
+    let(:webp_fixture) { Rails.root.join("spec/fixtures/files/image.webp").to_s }
+
+    after { helper.delete_all_resized_images }
+
+    it "returns a path ending with .png" do
+      result = helper.convert_webp_to_png(webp_fixture)
+      expect(result).to end_with(".png")
+    end
+
+    it "writes a non-empty PNG file" do
+      result = helper.convert_webp_to_png(webp_fixture)
+      expect(File.exist?(result)).to be true
+      expect(File.size(result)).to be > 0
+    end
+
+    it "writes a file with image/png MIME type" do
+      result = helper.convert_webp_to_png(webp_fixture)
+      expect(Marcel::MimeType.for(Pathname.new(result))).to eq("image/png")
+    end
+
+    it "falls back to the source file when extract_first_webp_frame returns nil" do
+      allow(helper).to receive(:extract_first_webp_frame).and_return(nil)
+      result = helper.convert_webp_to_png(webp_fixture)
+      expect(result).to end_with(".png")
+      expect(File.exist?(result)).to be true
+      expect(Marcel::MimeType.for(Pathname.new(result))).to eq("image/png")
+    end
+  end
+
+  describe "#attachment_image_local_file" do
+    let(:attachment)    { instance_double(Attachment, id: 42) }
+    let(:file_uploader) { instance_double(LocalFileUploader) }
+    let(:local_file)    { instance_double(File, path: "/some/path/image.png") }
+
+    context "when the file is accessible" do
+      before do
+        allow(attachment).to receive(:file).and_return(file_uploader)
+        allow(file_uploader).to receive(:local_file).and_return(local_file)
+      end
+
+      it "returns the local file object" do
+        expect(helper.attachment_image_local_file(attachment)).to eq(local_file)
+      end
+    end
+
+    context "when accessing the file raises an error" do
+      before do
+        allow(attachment).to receive(:file).and_return(file_uploader)
+        allow(file_uploader).to receive(:local_file).and_raise(StandardError, "disk error")
+        allow(Rails.logger).to receive(:error)
+      end
+
+      it "returns nil" do
+        expect(helper.attachment_image_local_file(attachment)).to be_nil
+      end
+
+      it "logs the error including the attachment id" do
+        helper.attachment_image_local_file(attachment)
+        expect(Rails.logger).to have_received(:error).with(/42/)
+      end
+    end
+  end
+
+  describe "#attachment_by_api_content_src" do
+    # api_url_helpers returns the ApiV3Path class; stub root_path on the class itself.
+    before do
+      allow(API::V3::Utilities::PathHelper::ApiV3Path).to receive(:root_path).and_return("/")
+    end
+
+    it "returns nil for an empty src" do
+      expect(helper.attachment_by_api_content_src("")).to be_nil
+    end
+
+    it "returns nil when src does not start with root_path" do
+      expect(helper.attachment_by_api_content_src("https://evil.example.com/attachments/1/file.png")).to be_nil
+    end
+
+    it "returns nil when src does not contain the attachments pattern" do
+      expect(helper.attachment_by_api_content_src("/api/v3/some_other_path")).to be_nil
+    end
+
+    context "when src matches a valid attachment path" do
+      let(:attachment) { instance_double(Attachment, id: 7) }
+
+      before { allow(Attachment).to receive(:find_by).with(id: 7).and_return(attachment) }
+
+      context "when the attachment is visible" do
+        before { allow(attachment).to receive(:visible?).and_return(true) }
+
+        it "returns the attachment for the api/v3 path" do
+          result = helper.attachment_by_api_content_src("/api/v3/attachments/7/content")
+          expect(result).to eq(attachment)
+        end
+
+        it "returns the attachment for the drag-and-drop path format" do
+          result = helper.attachment_by_api_content_src("/attachments/7/filename.ext")
+          expect(result).to eq(attachment)
+        end
+      end
+
+      context "when the attachment is not visible" do
+        before { allow(attachment).to receive(:visible?).and_return(false) }
+
+        it "returns nil" do
+          result = helper.attachment_by_api_content_src("/api/v3/attachments/7/content")
+          expect(result).to be_nil
+        end
+      end
+    end
+
+    context "when no attachment with that id exists" do
+      before { allow(Attachment).to receive(:find_by).and_return(nil) }
+
+      it "returns nil" do
+        expect(helper.attachment_by_api_content_src("/attachments/999/file.png")).to be_nil
+      end
+    end
+
+    context "when an unexpected error is raised" do
+      before do
+        allow(Attachment).to receive(:find_by).and_raise(StandardError, "db error")
+        allow(Rails.logger).to receive(:error)
+      end
+
+      it "returns nil" do
+        expect(helper.attachment_by_api_content_src("/attachments/1/file.png")).to be_nil
+      end
+
+      it "logs the error" do
+        helper.attachment_by_api_content_src("/attachments/1/file.png")
+        expect(Rails.logger).to have_received(:error)
+      end
+    end
+  end
+
+  describe "#attachment_image_filepath" do
+    let(:src) { "/api/v3/attachments/1/content" }
+    let(:attachment) { instance_double(Attachment, id: 1, content_type: "image/jpeg") }
+    let(:local_file) { instance_double(File, path: "/tmp/image.jpg") }
+
+    before do
+      allow(helper).to receive(:attachment_by_api_content_src).with(src).and_return(attachment)
+      allow(helper).to receive(:pdf_embeddable?).with("image/jpeg").and_return(true)
+      allow(helper).to receive(:attachment_image_local_file).with(attachment).and_return(local_file)
+      allow(helper).to receive(:resize_image).with("/tmp/image.jpg").and_return("/tmp/resized.jpg")
+    end
+
+    it "returns a resized image path for a jpeg" do
+      expect(helper.attachment_image_filepath(src)).to eq("/tmp/resized.jpg")
+    end
+
+    context "when attachment is nil" do
+      before { allow(helper).to receive(:attachment_by_api_content_src).with(src).and_return(nil) }
+
+      it "returns nil" do
+        expect(helper.attachment_image_filepath(src)).to be_nil
+      end
+    end
+
+    context "when content_type is not embeddable" do
+      before { allow(helper).to receive(:pdf_embeddable?).with("image/jpeg").and_return(false) }
+
+      it "returns nil" do
+        expect(helper.attachment_image_filepath(src)).to be_nil
+      end
+    end
+
+    context "when local_file is nil" do
+      before { allow(helper).to receive(:attachment_image_local_file).with(attachment).and_return(nil) }
+
+      it "returns nil" do
+        expect(helper.attachment_image_filepath(src)).to be_nil
+      end
+    end
+
+    context "when the attachment is a GIF" do
+      let(:attachment) { instance_double(Attachment, id: 1, content_type: "image/gif") }
+      let(:local_file) { instance_double(File, path: "/tmp/image.gif") }
+
+      before do
+        allow(helper).to receive(:attachment_by_api_content_src).with(src).and_return(attachment)
+        allow(helper).to receive(:pdf_embeddable?).with("image/gif").and_return(true)
+        allow(helper).to receive(:attachment_image_local_file).with(attachment).and_return(local_file)
+        allow(helper).to receive(:convert_gif_to_png).with("/tmp/image.gif").and_return("/tmp/converted.png")
+        allow(helper).to receive(:resize_image).with("/tmp/converted.png").and_return("/tmp/resized.png")
+      end
+
+      it "converts the GIF to PNG before resizing" do
+        result = helper.attachment_image_filepath(src)
+        expect(helper).to have_received(:convert_gif_to_png).with("/tmp/image.gif")
+        expect(result).to eq("/tmp/resized.png")
+      end
+    end
+
+    context "when the attachment is a WebP" do
+      let(:attachment) { instance_double(Attachment, id: 1, content_type: "image/webp") }
+      let(:local_file) { instance_double(File, path: "/tmp/image.webp") }
+
+      before do
+        allow(helper).to receive(:attachment_by_api_content_src).with(src).and_return(attachment)
+        allow(helper).to receive(:pdf_embeddable?).with("image/webp").and_return(true)
+        allow(helper).to receive(:attachment_image_local_file).with(attachment).and_return(local_file)
+        allow(helper).to receive(:convert_webp_to_png).with("/tmp/image.webp").and_return("/tmp/converted.png")
+        allow(helper).to receive(:resize_image).with("/tmp/converted.png").and_return("/tmp/resized.png")
+      end
+
+      it "converts the WebP to PNG before resizing" do
+        result = helper.attachment_image_filepath(src)
+        expect(helper).to have_received(:convert_webp_to_png).with("/tmp/image.webp")
+        expect(result).to eq("/tmp/resized.png")
+      end
+    end
+
+    context "when gif conversion returns nil" do
+      let(:attachment) { instance_double(Attachment, id: 1, content_type: "image/gif") }
+      let(:local_file) { instance_double(File, path: "/tmp/image.gif") }
+
+      before do
+        allow(helper).to receive(:attachment_by_api_content_src).with(src).and_return(attachment)
+        allow(helper).to receive(:pdf_embeddable?).with("image/gif").and_return(true)
+        allow(helper).to receive(:attachment_image_local_file).with(attachment).and_return(local_file)
+        allow(helper).to receive(:convert_gif_to_png).with("/tmp/image.gif").and_return(nil)
+      end
+
+      it "returns nil" do
+        expect(helper.attachment_image_filepath(src)).to be_nil
+      end
+    end
+  end
+
+  describe "#extract_first_webp_frame" do
+    let(:animated_webp) { Rails.root.join("spec/fixtures/files/animated.webp").to_s }
+    let(:static_webp)   { Rails.root.join("spec/fixtures/files/image.webp").to_s }
+    let(:non_webp)      { Rails.root.join("spec/fixtures/files/image.png").to_s }
+
+    after { helper.delete_all_resized_images }
+
+    context "with an animated WebP" do
+      it "returns a non-nil path" do
+        expect(helper.extract_first_webp_frame(animated_webp)).not_to be_nil
+      end
+
+      it "returns a path to an existing file" do
+        result = helper.extract_first_webp_frame(animated_webp)
+        expect(File.exist?(result)).to be true
+      end
+
+      it "returns a file with image/webp MIME type" do
+        result = helper.extract_first_webp_frame(animated_webp)
+        expect(Marcel::MimeType.for(Pathname.new(result))).to eq("image/webp")
+      end
+
+      it "returns a single-frame WebP" do
+        result = helper.extract_first_webp_frame(animated_webp)
+        expect(MiniMagick::Image.open(result).frames.count).to eq(1)
+      end
+
+      it "returns a file with a valid RIFF/WEBP container header" do
+        result = helper.extract_first_webp_frame(animated_webp)
+        data = File.binread(result)
+        expect(data[0, 4]).to eq("RIFF".b)
+        expect(data[8, 4]).to eq("WEBP".b)
+      end
+    end
+
+    context "with a static (non-animated) WebP" do
+      it "returns nil" do
+        expect(helper.extract_first_webp_frame(static_webp)).to be_nil
+      end
+    end
+
+    context "with a non-WebP file" do
+      it "returns nil" do
+        expect(helper.extract_first_webp_frame(non_webp)).to be_nil
+      end
+    end
+
+    context "when an error is raised while reading the file" do
+      before do
+        allow(File).to receive(:binread).and_raise(StandardError, "read error")
+        allow(Rails.logger).to receive(:error)
+      end
+
+      it "returns nil" do
+        expect(helper.extract_first_webp_frame(animated_webp)).to be_nil
+      end
+
+      it "logs the error" do
+        helper.extract_first_webp_frame(animated_webp)
+        expect(Rails.logger).to have_received(:error).with(/read error/)
+      end
+    end
+  end
+end