CVE-2026-4054

Summary

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to validate the response body of proxied images, which allows a remote attacker to enact client-side DoS via an SVG file served from an attacker-controlled origin under a non-SVG Content-Type header (e.g. image/png) embedded in an og:image meta tag or Markdown image link.. Mattermost Advisory ID: MMSA-2026-00630

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-754: CWE-754: Improper Check for Unusual or Exceptional Conditions

ADP Enrichment

CISA ADP Vulnrichment

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

References