CVE-2026-5132

Unbounded zlib decompression in Calls SDP WebSocket messages

State: Published
Severity: 6.5 Medium
Published: Sep 14, 2026
Updated: Sep 14, 2026
Reserved: Mar 30, 2026

Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to limit size of unpacked SDP messages compressed with zlib, which allows attacker to deny service or crash server via sending many SDP messages that unpack to large size.. Mattermost Advisory ID: MMSA-2026-00643

Scores

CVSS	Score	Vector	Source
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H	Mattermost

Weaknesses

CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

Product	Versions
MattermostMattermost	11.9.0 through 11.9.0Affected 11.8.0 through 11.8.4Affected 11.7.0 through 11.7.7Affected 10.11.0 through 10.11.22Affected 11.10.0Not affected 11.9.1Not affected 11.8.5Not affected 11.7.8Not affected 10.11.23Not affected

References

MMSA-2026-00643vendor-advisory

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.