CVE-2026-5163
Last modified
CVE-2026-5163 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645. EPSS estimates a 0.21% chance of exploitation in the next 30 days.
Description
Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost Server | >= 11.5.0, < 11.5.2 |
References
- https://mattermost.com/security-updatesVendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-5163?
How severe is CVE-2026-5163?
How do I fix CVE-2026-5163?
How Strix Helps
- Uncovering a hidden BOLA in Appsmith's snapshot logicStrix autonomously discovered a BOLA/IDOR vulnerability in Appsmith's snapshot deletion path.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-51603A stack-based buffer overflow vulnerability in the RTSP serv…7.5
- CVE-2026-51604A stack-based buffer overflow vulnerability in the RTSP serv…7.5
- CVE-2026-51605A stack-based buffer overflow vulnerability in the RTSP serv…7.5
- CVE-2026-51606An improper input handling vulnerability in the RTSP service…7.5
- CVE-2026-5161Improper link resolution before file access ('link following…8.8
- CVE-2026-5162The Royal Addons for Elementor plugin for WordPress is vulne…6.4
- CVE-2026-5164A flaw was found in virtio-win. The `RhelDoUnMap()` function…5.5
- CVE-2026-5165A flaw was found in virtio-win, specifically within the Virt…7.8
- CVE-2026-5166Improper Limitation of a Pathname to a Restricted Directory …9.6
- CVE-2026-5167The Masteriyo LMS – Online Course Builder for eLearning, LMS…5.3
- CVE-2026-5169The Inquiry Form to Posts or Pages plugin for WordPress is v…4.4
- CVE-2026-5170A user with access to the cluster with a limited set of priv…5.3
Are you affected by CVE-2026-5163?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST