CVE-2026-10103

🔶 medium

Summary

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing arbitrary post IDs in channels shared with that remote.. Mattermost Advisory ID: MMSA-2026-00689

CVSS Score

4.3

Medium

EPSS Score

0.2

Exploit Probability

Published Date

2026-07-13

First Seen: 2026-07-14

📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 5.4% of all 338,292 vulnerabilities in our database.

#320,047

Below average severity

Severity Percentile

🎯 CISA SSVC Assessment Updated: Jul 14, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

Requires human interaction

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

ratrarity

SSVC data provided by CISA

Last Modified 2026-07-14

Source NVD 🔗

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

CWE IDs (Weakness Types)

CWE-639

📦 Affected Products 3

Vendor	Product	Status	Affected Versions
mattermost	mattermost_server	Affected	> 10.11.0 < 10.11.20
mattermost	mattermost_server	Affected	> 11.6.0 < 11.6.5
mattermost	mattermost_server	Affected	> 11.7.0 < 11.7.3

🔗 References 1

https://mattermost.com/security-updates

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-10085	🔶 medium	5.4	0.2	Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained chann...	2026-07-13
CVE-2026-10106	🔶 medium	6.5	0.2	Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify that the channel referenced i...	2026-07-13
CVE-2026-6850	🔶 medium	6.5	0.2	Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate the length and content of m...	2026-07-13
CVE-2026-9571	🔶 medium	5.9	0.2	Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon...	2026-07-13
CVE-2026-9597	🔶 medium	5.4	0.1	Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4 fail to verify whether a guest account is deactivated before crea...	2026-07-13
CVE-2026-9708	🔶 medium	4.9	0.2	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 w...	2026-07-13

These CVEs affect the same products