CVE-2026-2455

Summary

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585

Affected Software

VendorProductVersion RangeStatus
MattermostMattermost11.3.0 <= 11.3.0affected
MattermostMattermost11.2.0 <= 11.2.2affected
MattermostMattermost10.11.0 <= 10.11.10affected
MattermostMattermost11.4.0unaffected
MattermostMattermost11.3.1unaffected
MattermostMattermost11.2.3unaffected
MattermostMattermost10.11.11unaffected

Weaknesses

  • CWE-918: CWE-918: Server-Side Request Forgery (SSRF)

ADP Enrichment

CISA ADP Vulnrichment

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

References