Cyber Resilience

CVE-2025-68933

Access Control in Discourse ≤ 3.5.4

Published
28 January 2026
Modified
30 January 2026
Patch / advisory
CVSS Score v3.1 6.9
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:H/A:N
EPSS Score 0.0014 3th percentile
Risk Priority 40 floored blend · peak EPSS

Summary

CVE-2025-68933 is a medium-severity Incorrect Authorization (CWE-863) vulnerability in Discourse Discourse. Its CVSS base score is 6.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 3th 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

Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, non-admin moderators with the `moderators_change_post_ownership` setting enabled can change ownership of posts in private messages and restricted categories they cannot access, then export their…

more

data to view the content. This is a broken access control vulnerability affecting sites that grant moderators post ownership transfer permissions. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. The patch adds visibility checks for both the topic and posts before allowing ownership transfer. As a workaround, disable the `moderators_change_post_ownership` site setting to prevent non-admin moderators from using the post ownership transfer feature.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
Why these techniques?

Broken access control in public-facing Discourse enables direct exploitation (T1190) and unauthorized privilege escalation to restricted data (T1068).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-28282Same product: Discourse Discourse
CVE-2026-28227Same product: Discourse Discourse
CVE-2026-33428Same product: Discourse Discourse
CVE-2026-33251Same product: Discourse Discourse
CVE-2026-33424Same product: Discourse Discourse
CVE-2026-27936Same product: Discourse Discourse
CVE-2025-69289Same product: Discourse Discourse
CVE-2025-69218Same product: Discourse Discourse
CVE-2025-68666Same product: Discourse Discourse
CVE-2023-32061Same product: Discourse Discourse

Affected Assets

discourse
discourse
2025.12.0, 2026.1.0 · ≤ 3.5.4 · 2025.11.0 — 2025.11.2

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)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly enforces authorization checks on post ownership transfer so that moderators cannot act on topics/posts outside their visibility scope.

prevent

Limits the effective privileges granted by the moderators_change_post_ownership setting to only those moderators who already have read access to the affected topics.

prevent

Enforces information-flow rules that block the unauthorized transfer of private-message or restricted-category content to a moderator via ownership change followed by data export.

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-05 mostly match
prevents

Defining, enforcing, and reviewing access authorizations and least privilege directly prevents incorrect authorization checks.

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

Requiring consistency between access rights and classification plus formal approval steps ensures that the authorization logic correctly distinguishes between entities that should and should not be granted access.

prevents

Enforcing policy-driven approval and role-change reviews stops incorrect or stale authorization decisions from remaining in effect after job changes or terminations.

prevents

By tying access rights to identity, device, location and classification, the control reduces the likelihood that an authorization decision will be based on an incorrect or bypassed policy.

References