CVE-2026-96259
What it is
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to apply the internal-connection filter to OAuth endpoint requests, which allows a System Administrator to make the server issue requests to internal network addresses and read the responses via the configured OAuth token and userinfo endpoints.. Mattermost Advisory ID: MMSA-2026-00776
At a glance
- Exploitability
- Can be exploited over the network with an admin-level account. Limited direct impact.
- Exploit odds
- 0.3% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.3% in the next 30 days (EPSS).
- Severity: 5.5 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.3% · EPSS, next 30 days
- Weakness
- CWE-918 · Server-side request forgery
- Record status
- Analyzed
Affected
- Mattermost Server < 11.7.11
- Mattermost Server < 11.8.6
- Mattermost Server < 11.9.2
- Mattermost Server < 11.10.2
Attack profile CVSS 3.1 · 5.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Raw vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-96259.md and follow it. Check whether this project is affected by CVE-2026-96259. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
