CVE-2026-39903 Simple Machines Forum Authorization Bypass via AttachmentApprove.php
Low-privileged users can bypass permission checks to approve, reject, or delete any pending attachments across all boards.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-39903?
CVE-2026-39903 is a high-severity missing authorization vulnerability in SimpleMachines SMF, published on 10 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Simple Machines Forum 2.1 prior to commit 7d048f8 and 3.0 prior to commit a7875e8 contains an authorization bypass vulnerability in Sources/Actions/AttachmentApprove.php where a single-character operator error causes the permission check to always pass regardless of user permissions. An authenticated low-privileged user can approve, reject, or delete any pending attachments on any board without holding the required approve_posts permission, bypass moderation queues for their own uploads, and enumerate and delete other users' pending attachments.
Weakness: CWE-863
Which versions are affected by CVE-2026-39903?
How do I fix CVE-2026-39903?
No fix has been published for CVE-2026-39903 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-39903 being exploited?
There is no known exploitation of CVE-2026-39903 in the wild and no public exploit code.
Sources
Also known as GHSA-62g6-4j9c-6v7p.