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CVE-2026-96259

Mattermost server-side request forgery via OAuth endpoints configurable by a System Administrator

CVSS 3.1 5.5 MEDIUMCheck source for fixed versionsKEV status unknown
Original advisory

cve-program · CVE-2026-96259

Published

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

Read the publisher's advisory

Affected versions, risk and source history

Exploitation and risk

Source status

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cve-program · CVE-2026-96259

Published

Mattermost server-side request forgery via OAuth endpoints configurable by a System Administrator

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

Source published
22 Sep 2026 20:34:20 UTC
Source modified
23 Sep 2026 13:10:47 UTC
Saved here
23 Oct 2026 15:48:27 UTC
Source terms
CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 5.5 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N

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Sources read 12 Nov 18:36 UTC · 273 of 275 readable · 271 fully read · documentation 469/469 current

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