CVE-2026-43621 Simple Machines Forum < 2.1.7 Authorization Confusion via Profile::load()
Authenticated low-privileged users can gain administrator access and take over accounts by exploiting an authorization state-confusion in the profile loader.
- 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-2026-43621?
CVE-2026-43621 is a high-severity authentication bypass vulnerability in SimpleMachines SMF, published on 26 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Simple Machines Forum (SMF) through 2.1.7, fixed in commit 6f0dc61, contains an authorization state-confusion vulnerability in the profile loader that allows authenticated low-privileged users to gain administrator access by supplying multiple values for the user parameter. Attackers can exploit the mismatch between Profile::$member and User::$me->is_owner during sequential profile loading to be treated as the owner of an administrator profile, enabling unauthorized password changes and full account takeover.
Weakness: CWE-863
Which versions are affected by CVE-2026-43621?
How do I fix CVE-2026-43621?
No fix has been published for CVE-2026-43621 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-43621 being exploited?
There is no known exploitation of CVE-2026-43621 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-pw24-wq86-2799.