CVE-2026-107845
Contao: Cross-site scripting in the comments bundle
Published Oct 9, 2026 · updated Oct 9, 2026
An unauthenticated front end visitor can post a comment containing a XSS injection. The victim is any back end user who opens the Comments module, and moderation makes exposure certain rather than preventing it. No header is sent on the Contao back end, so nothing mitigates the inline handler. ### Impact Anyone on the internet can inject script that executes in the Contao back end origin, under the session of whichever user opens the Comments module, with no click and no hover. From there the payload acts as that user through the back end: reading any module they can reach, creating a new administrator, or editing a template, which on Contao is a documented path from back end write access to code execution. Moderation does not help and in fact guarantees exposure, since unpublished comments are still inserted and a moderator has to open the list to act on them.
Timeline
Detection, updates, and resolution for this record.
Oct 9, 2026 · Catalog
Detected
An unauthenticated front end visitor can post a comment containing a XSS injection. The victim is any back end user who opens the Comments module, and moderation makes exposure certain rather than preventing it. No header is sent on the Contao back end, so nothing mitigates the inline handler. ### Impact Anyone on the internet can inject script that executes in the Contao back end origin, under th
Oct 9, 2026 · Catalog
Fix available
Packagist contao/comments-bundle 4.0.0 → 5.3.50
Oct 9, 2026 · Catalog
Fix available
Packagist contao/comments-bundle 5.4.0-RC1 → 5.7.12
Oct 9, 2026 · Catalog
Updated
An unauthenticated front end visitor can post a comment containing a XSS injection. The victim is any back end user who opens the Comments module, and moderation makes exposure certain rather than preventing it. No header is sent on the Contao back end, so nothing mitigates the inline handler. ### Impact Anyone on the internet can inject script that executes in the Contao back end origin, under th
Affected
- Packagist contao/comments-bundle4.0.0 → 5.3.50
- Packagist contao/comments-bundle5.4.0-RC1 → 5.7.12
Sources
- CVE.orgCVE-2026-107845
Official CVE identifier
cve.org - FIRST EPSSCVE-2026-107845
30-day exploitation probability 0.3%
first.org - GitHub Advisory DatabaseGHSA-628f-v4f6-p37r
GitHub Advisory Database record mirrored by OSV.
github.com - OSV.devGHSA-628f-v4f6-p37r
Contao: Cross-site scripting in the comments bundle
osv.dev