diff --git a/src/renderer/src/components/sidebar/CommentMarkdown.github-attachment-image.test.tsx b/src/renderer/src/components/sidebar/CommentMarkdown.github-attachment-image.test.tsx
new file mode 100644
index 000000000..49bf77d7e
--- /dev/null
+++ b/src/renderer/src/components/sidebar/CommentMarkdown.github-attachment-image.test.tsx
@@ -0,0 +1,64 @@
+// @vitest-environment happy-dom
+
+import { act } from 'react'
+import { createRoot, type Root } from 'react-dom/client'
+import { afterEach, beforeEach, describe, expect, it } from 'vitest'
+import CommentMarkdown from './CommentMarkdown'
+
+const attachmentUrl =
+  'https://github.com/user-attachments/assets/ce11040a-fb66-4289-927f-547b16dfc488'
+
+let root: Root | null = null
+let container: HTMLDivElement | null = null
+
+function renderCommentMarkdown(content: string): HTMLDivElement {
+  container = document.createElement('div')
+  document.body.appendChild(container)
+  root = createRoot(container)
+  act(() => {
+    root?.render(<CommentMarkdown variant="document" content={content} />)
+  })
+  return container
+}
+
+describe('CommentMarkdown GitHub attachment images', () => {
+  beforeEach(() => {
+    globalThis.IS_REACT_ACT_ENVIRONMENT = true
+  })
+
+  afterEach(() => {
+    if (root) {
+      act(() => root?.unmount())
+    }
+    document.body.replaceChildren()
+    root = null
+    container = null
+  })
+
+  it('renders GitHub user attachment document images as openable links', () => {
+    const mounted = renderCommentMarkdown(`![Private issue screenshot](${attachmentUrl})`)
+
+    const link = mounted.querySelector<HTMLAnchorElement>(`a[href="${attachmentUrl}"]`)
+    const image = link?.querySelector<HTMLImageElement>('img')
+
+    expect(link).not.toBeNull()
+    expect(link?.className).toContain('inline-block')
+    expect(image?.src).toBe(attachmentUrl)
+    expect(image?.alt).toBe('Private issue screenshot')
+  })
+
+  it('falls back to a text link when a GitHub user attachment image cannot load', () => {
+    const mounted = renderCommentMarkdown(`![Private issue screenshot](${attachmentUrl})`)
+    const image = mounted.querySelector<HTMLImageElement>(`img[src="${attachmentUrl}"]`)
+
+    expect(image).not.toBeNull()
+    act(() => {
+      image?.dispatchEvent(new window.Event('error'))
+    })
+
+    expect(mounted.querySelector(`img[src="${attachmentUrl}"]`)).toBeNull()
+    const fallback = mounted.querySelector<HTMLAnchorElement>(`a[href="${attachmentUrl}"]`)
+    expect(fallback?.textContent).toBe('Private issue screenshot')
+    expect(fallback?.className).toContain('underline')
+  })
+})
diff --git a/src/renderer/src/components/sidebar/comment-markdown-element-renderers.tsx b/src/renderer/src/components/sidebar/comment-markdown-element-renderers.tsx
index 5f2e0b972..7940d6278 100644
--- a/src/renderer/src/components/sidebar/comment-markdown-element-renderers.tsx
+++ b/src/renderer/src/components/sidebar/comment-markdown-element-renderers.tsx
@@ -2,9 +2,11 @@ import React from 'react'
 import type { Components } from 'react-markdown'
 import { isMermaidFence, isMermaidPre, renderMermaidFence } from './comment-mermaid-fence'
 import {
+  GitHubUserAttachmentImage,
   GitHubUserAttachmentVideo,
+  isGitHubUserAttachmentUrl,
   isGitHubUserAttachmentVideoLink
-} from './comment-markdown-github-attachment-video'
+} from './comment-markdown-github-attachment-media'
 
 export type CommentMarkdownLinkClickHandler = (
   event: React.MouseEvent<HTMLElement>,
@@ -230,6 +232,12 @@ export function createDocumentCommentMarkdownComponents(
       </blockquote>
     ),
     img: ({ alt, src }) => {
+      if (isGitHubUserAttachmentUrl(src)) {
+        // Why: private-repo attachment images fail as cross-origin loads; a
+        // top-level link opens them in a GitHub-authenticated tab, and falls
+        // back to a text link when the image itself can't render.
+        return <GitHubUserAttachmentImage src={src} alt={alt} />
+      }
       const imageClassName = [
         'my-3 max-h-96 max-w-full rounded-md object-contain',
         'outline outline-1 outline-black/10 dark:outline-white/10',
diff --git a/src/renderer/src/components/sidebar/comment-markdown-github-attachment-video.tsx b/src/renderer/src/components/sidebar/comment-markdown-github-attachment-media.tsx
similarity index 55%
rename from src/renderer/src/components/sidebar/comment-markdown-github-attachment-video.tsx
rename to src/renderer/src/components/sidebar/comment-markdown-github-attachment-media.tsx
index 448493389..7f94e907e 100644
--- a/src/renderer/src/components/sidebar/comment-markdown-github-attachment-video.tsx
+++ b/src/renderer/src/components/sidebar/comment-markdown-github-attachment-media.tsx
@@ -1,6 +1,6 @@
 import React from 'react'
 
-function isGitHubUserAttachmentUrl(href: string | undefined): href is string {
+export function isGitHubUserAttachmentUrl(href: string | undefined): href is string {
   if (!href) {
     return false
   }
@@ -67,3 +67,48 @@ export function GitHubUserAttachmentVideo({
     </video>
   )
 }
+
+export function GitHubUserAttachmentImage({
+  src,
+  alt
+}: {
+  src: string
+  alt: string | undefined
+}): React.ReactElement {
+  const [failed, setFailed] = React.useState(false)
+  const label = alt?.trim() || src
+
+  // Why: private-repo attachment images can't load cross-origin without the
+  // user's GitHub session cookies, so wrap in a top-level link (opening the
+  // URL where that session exists) and drop to a text link on load error.
+  if (failed) {
+    return (
+      <a
+        href={src}
+        target="_blank"
+        rel="noreferrer"
+        className="break-all text-primary underline underline-offset-2 hover:text-primary/80"
+        onClick={(e) => e.stopPropagation()}
+      >
+        {label}
+      </a>
+    )
+  }
+
+  return (
+    <a
+      href={src}
+      target="_blank"
+      rel="noreferrer"
+      className="inline-block max-w-full"
+      onClick={(e) => e.stopPropagation()}
+    >
+      <img
+        src={src}
+        alt={alt ?? ''}
+        className="my-3 max-h-96 max-w-full rounded-md object-contain outline outline-1 outline-black/10 dark:outline-white/10"
+        onError={() => setFailed(true)}
+      />
+    </a>
+  )
+}