Cyber Resilience

CVE-2025-13870

Access Control in Mattermost Server 10.5.0 – 10.5.13

Published
02 December 2025
Modified
03 December 2025
Patch / advisory
CVSS Score v3.1 3.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS Score 0.0020 10th percentile
Risk Priority 15 floored blend · peak EPSS

Summary

CVE-2025-13870 is a low-severity Missing Authentication for Critical Function (CWE-306) vulnerability in Mattermost Mattermost Server. Its CVSS base score is 3.1 (Low).

Operationally, ranked at the 10th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Mattermost versions 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to validate the user permission when accessing the files and subscribing to the block in Boards, which allows an authenticated user to access other board files and was able to subscribe…

more

to the block from other boards that the user does not have access to

CWE(s)

Related Threats

CVEs Like This One

CVE-2025-6226Same product: Mattermost Mattermost Server
CVE-2025-55073Same product: Mattermost Mattermost Server
CVE-2025-25068Same product: Mattermost Mattermost Server
CVE-2026-6673Same product: Mattermost Mattermost Server
CVE-2025-55070Same product: Mattermost Mattermost Server
CVE-2025-27538Same product: Mattermost Mattermost Server
CVE-2025-47870Same product: Mattermost Mattermost Server
CVE-2024-2450Same product: Mattermost Mattermost Server
CVE-2026-6343Same product: Mattermost Mattermost Server
CVE-2026-2462Same product: Mattermost Mattermost Server

Affected Assets

mattermost
mattermost server
10.5.0 — 10.5.13 · 10.11.0 — 10.11.5

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • AC-6 Least Privilege
  • AC-4 Information Flow Enforcement
Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 6 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V6.2.3
  • V6.4.4
  • V10.4.16
  • V12.1.3

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly requires the system to enforce access-control policies before permitting operations on board files and blocks, which the CVE shows was not performed.

prevent

Requires that users receive only the privileges needed for their boards, limiting the impact of any missing per-object permission checks.

prevent

Enforces rules governing the flow of information between subjects and objects (boards/files), addressing unauthorized cross-board access.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 full match
prevents

Directly requires authentication of users/services/hardware, which eliminates missing authentication for critical functions.

PR.AA-01 partial match
prevents

Managing identities and credentials is a prerequisite for authentication but does not itself enforce it on critical functions.

PR.AA-05 partial match
prevents

Defining and enforcing authorizations assumes prior authentication and therefore only partially mitigates the absence of authentication.

PR.IR-01 partial match
prevents

Protecting networks from unauthorized access can be undermined by missing authentication but does not address the root authentication gap.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

The control explicitly calls for authentication before any critical function is reached, eliminating the possibility of bypassing authentication for high-value operations.

prevents

Mandating authentication requirements for critical functions at the requirements-gathering stage ensures that essential operations are not left unprotected by missing login or verification mechanisms.

mitigates

Mandating authentication for network services and critical functions stops attackers from invoking sensitive operations without credentials, closing gaps where authentication is absent for important capabilities.

prevents

Security engineering principles insist on authentication and authorization for every critical function, eliminating entry points that lack any access control mechanism.

none

Requiring strong authentication and access-privilege enablement for remote connections ensures that critical functions cannot be invoked without proper verification, closing a gap that would otherwise allow unauthenticated use.

none

Mandatory use of access cards, biometrics, or two-factor authentication ensures that critical physical areas cannot be entered without proper authentication.

References