CVE-2026-28735
Last modified
CVE-2026-28735 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL.. Mattermost Advisory ID: MMSA-2026-00628. EPSS estimates a 0.14% chance of exploitation in the next 30 days.
Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL.. Mattermost Advisory ID: MMSA-2026-00628
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost Server | >= 10.11.0, < 10.11.15 |
| Mattermost | Mattermost Server | >= 11.4.0, < 11.4.5 |
| Mattermost | Mattermost Server | >= 11.5.0, < 11.5.4 |
| Mattermost | Mattermost Server | >= 11.6.0, < 11.6.1 |
References
- https://mattermost.com/security-updatesVendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-28735?
How severe is CVE-2026-28735?
How do I fix CVE-2026-28735?
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-2026-28727Local privilege escalation due to insecure Unix socket permi…7.8
- CVE-2026-28728Local privilege escalation due to DLL hijacking vulnerabilit…6.7
- CVE-2026-28729Integer overflow in the UEFI firmware for the Intel(R) Slim …2.4
- CVE-2026-2873A vulnerability was detected in Tenda A21 1.0.0.0. This issu…8.8
- CVE-2026-28732Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 1…4.3
- CVE-2026-28733in OpenHarmony v6.0 and prior versions allow a local attacke…6.5
- CVE-2026-28736** UNSUPPORTED WHEN ASSIGNED ** Focalboard version 8.0 fails…4.3
- CVE-2026-28737Gitea versions from 1.25.0 before 1.26.0 allow stored cross-…8.7
- CVE-2026-2874A flaw has been found in Tenda A21 1.0.0.0. Impacted is the …8.8
- CVE-2026-28740Gitea versions up to and including 1.26.2 allow Git LFS obje…7.1
- CVE-2026-28741Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 1…8.1
- CVE-2026-28742Naxclow devices use a uniform request-signing scheme based o…9.8
Are you affected by CVE-2026-28735?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST