CVE-2026-6340

Summary

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate 7zip archive structure before processing which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted 7zip file with excessive folder declarations.. Mattermost Advisory ID: MMSA-2026-00573

Affected Software

VendorProductVersion RangeStatus
MattermostMattermost11.5.0 <= 11.5.1affected
MattermostMattermost10.11.0 <= 10.11.13affected
MattermostMattermost11.4.0 <= 11.4.3affected
MattermostMattermost11.6.0unaffected
MattermostMattermost11.5.2unaffected
MattermostMattermost10.11.14unaffected
MattermostMattermost11.4.4unaffected

Weaknesses

  • CWE-789: CWE-789: Memory Allocation with Excessive Size Value

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References