Auth bypass in Flaskbb

CVE-2026-22659

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.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (42.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 42.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-22659: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

  • Flaskbb — versions 0, https://github.com/flaskbb/flaskbb/commit/a5da9a52

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-22659?
CVE-2026-22659 is a high-severity vulnerability in Flaskbb, classified under Incorrect Authorization. CVSS score: 8.1/10. Published 2026-07-10.
How severe is CVE-2026-22659?
High severity. CVSS v3 base score is 8.1 out of 10.