CVE-2026-9708

medium

Published 2026-07-13 · Modified 2026-07-13

💬 Discuss on Community ✚ Propose mitigation

CVSS v3

4.9

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

4.9

Description

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683

Predictions

Exploit likelihood

59%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

Application impact

Vendor	Product	Versions	Fixed
mattermost	mattermost_server	`{"startIncluding":"10.11.0","endExcluding":"10.11.20"}`	`10.11.20`
mattermost	mattermost_server	`{"startIncluding":"11.6.0","endExcluding":"11.6.5"}`	`11.6.5`
mattermost	mattermost_server	`{"startIncluding":"11.7.0","endExcluding":"11.7.3"}`	`11.7.3`

References

https://mattermost.com/security-updates

CWEs

CWE-639

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.