CVE-2026-5132

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

  • Published Sep 14, 2026
  • CVSS 6.5 medium
  • 0.4% chance of exploitation in the next 30 days (EPSS)

Affected software

CVE-2026-5132 at the National Vulnerability Database