CVE-2026-22880 Mobile SSO authentication flow allows credential theft via malicious server
Attackers can steal user credentials by exploiting improper SSO callback validation in the Mattermost mobile application.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-22880?
CVE-2026-22880 is a medium-severity authentication bypass vulnerability in Mattermost, published on 21 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Mattermost Mobile Apps versions <=2.37 11.4 2.0.37 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to properly validate the SSO authentication callback origin which allows an attacker controlling a malicious Mattermost server to steal user credentials for a legitimate Mattermost server via relaying the SSO code exchange flow through the mobile application. Mattermost Advisory ID: MMSA-2025-00564
Weakness: CWE-352
Which versions are affected by CVE-2026-22880?
It affects 1 product.
Products include Mattermost Mattermost Mobile.
How do I fix CVE-2026-22880?
No fix has been published for CVE-2026-22880 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-2026-22880 being exploited?
There is no known exploitation of CVE-2026-22880 in the wild and no public exploit code.
Other vulnerabilities in Mattermost
Sources
Also known as GHSA-j628-rc2h-qj7g.