CVE-2026-22659: FlaskBB Authorization Bypass via Topic ID Manipulation

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-10 · updated 2026-07-14
Weakness: CWE-863

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.

Affected products

flaskbb: through 2.2.0

References

https://github.com/flaskbb/flaskbb/commit/acc88cfedd011124395e0101cb27432a47f712be
https://github.com/flaskbb/flaskbb/security/advisories/GHSA-9rjj-9p2h-6c55
https://www.vulncheck.com/advisories/flaskbb-authorization-bypass-via-topic-id-manipulation
https://github.com/flaskbb/flaskbb/security/advisories/GHSA-9rjj-9p2h-6c55

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