High severity · published Aug 11, 2026
CVE-2026-73249
calibre Content Server `/book-update-annotations` Missing Write Authorization Check Allows Unauthorized Annotation Modification
7.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CA
calibre · kovidgoyal
< 9.12.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73249
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73249
github.com
https://github.com/kovidgoyal/calibre/commit/71295e8b62801e1ccecaa4fac47e6942f11cfe1e
github.com
https://github.com/kovidgoyal/calibre/releases/tag/v9.12.0
github.com
https://github.com/kovidgoyal/calibre/security/advisories/GHSA-5x64-w63v-x2g6
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