Paper/Archive/CVE-2026-4858

CVE-2026-4858

Mattermost Mattermost — Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.

EPSS 0.3%CVSS 9.9

critical.is priorityof 100

CVSS 9.9 (NVD)9.9 / 10 × 3029.7 Not in CISA KEV+300.0 EPSS percentile 25.9.259 × 205.2 No public exploit+100.0 SSVC exploitation: none+100.0

Description · from the CVE record

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL.. Mattermost Advisory ID: MMSA-2026-00640

Affected

ProductAffectedFixed inSource

Mattermost11.6.0 – 11.6.011.7.0CNA

Mattermost11.5.0 – 11.5.311.7.0CNA

Mattermost11.4.0 – 11.4.411.7.0CNA

Mattermost10.11.0 – 10.11.1410.11.15CNA

Scores by source

NVD9.9CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Mattermost (CNA)8.0CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: total

References

advisorymattermost.com/security-updates