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Description

FlaskBB through 2.2.0, fixed in commit acc88cf, contains an authorization bypass vulnerability that allows authenticated moderators to perform unauthorized actions on topics in forums they do not control by submitting crafted topic ID lists. Attackers can include a low-ID topic from a permitted forum as an anchor in a batch request, causing the permission check applied only to the first result to pass, and then execute lock, unlock, delete, or hide actions against topics in unmoderated forums.

PUBLISHED Reserved 2026-01-08 | Published 2026-07-10 | Updated 2026-07-14 | Assigner VulnCheck




HIGH: 7.2CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

HIGH: 8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Problem types

Incorrect Authorization

Product status

Default status
affected

Any version
affected

https://github.com/flaskbb/flaskbb/commit/a5da9a52 (git)
unaffected

Credits

Hamed Kohi (@0xHamy) finder

VulnCheck coordinator

References

github.com/...laskbb/security/advisories/GHSA-9rjj-9p2h-6c55 exploit

github.com/...laskbb/security/advisories/GHSA-9rjj-9p2h-6c55 (GitHub Security Advisory (GHSA-9rjj-9p2h-6c55)) vendor-advisory

github.com/...ommit/acc88cfedd011124395e0101cb27432a47f712be (Patch Commit) patch

www.vulncheck.com/...zation-bypass-via-topic-id-manipulation third-party-advisory

cve.org (CVE-2026-22659)

nvd.nist.gov (CVE-2026-22659)

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