Cyber Posture

CVE-2026-4858

High
Microsoft: not affectedMSmacOS: not affectedMacLinux: not affectedLnxMobile: not affectedMobNetwork: not affectedNetApplication: not affectedAppOther: affectedOth

Published: 21 May 2026

Published
21 May 2026
Modified
21 May 2026
KEV Added
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Patch
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CVSS Score 8.0 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
EPSS Score 0.0003 9.1th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-4858 is a high-severity Path Traversal (CWE-22) vulnerability. Its CVSS base score is 8.0 (High).

Operationally, ranked at the 9.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-10 Information Input Validation
addresses: CWE-22

Validates pathnames and filenames to prevent traversal outside intended directories.

NVD Description

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…

more

via path traversal in integration action URL.. Mattermost Advisory ID: MMSA-2026-00640

Deeper analysisAI

Automated synthesis unavailable for this CVE.

Details

CWE(s)
CWE-22
OWASP Top 10 Web 2025
A01:2025

Affected Products

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Mattermost
inferred from references and description; NVD did not file a CPE for this CVE

EU & UK References

References