CVE-2026-96259
mediumMattermost 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 re…
Vendor / product: Mattermost — mattermost server
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
CVSS
5.5
5.5 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N Severity source: NVD CVSS v3.1 (responsibledisclosure@mattermost.com)
Timeline (UTC)
Published: 2026-09-22 21:17
Modified: 2026-10-07 16:41
NVD status: Analyzed
Last synced 2 days ago
Verified against the source API 2026-10-27 06:55 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
mattermost / mattermost_server ≥11.7.0 <11.7.11, ≥11.8.0 <11.8.6, ≥11.9.0 <11.9.2, ≥11.10.0 <11.10.2
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Vendor advisory: https://mattermost.com/security-updates
References
- https://mattermost.com/security-updates responsibledisclosure@mattermost.com
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 06:55 UTC · record ↗