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CVE Record

CVE-2026-26207: DIscourse's discourse-policy plugin lacks post access check

Discourse is an open source discussion platform. Prior to versions 2025.12.2, 2026.1.1, and 2026.2.0, `discourse-policy` plugin allows any authenticated user to interact with policies on posts they do not have permission to view. The `PolicyController` loads posts by ID without verifying the current user's access, enabling policy group members to accept/unaccept policies on posts in private categories or PMs they cannot see and any authenticated user to enumerate which post IDs have policies attached via differentiated error responses (information disclosure). The issue is patched in versions 2025.12.2, 2026.1.1, and 2026.2.0 by adding a `guardian.can_see?(@post)` check in the `set_post` before_action, ensuring post visibility is verified before any policy action is processed. As a workaround, disabling the discourse-policy plugin (`policy_enabled = false`) eliminates the vulnerability. There is no other workaround without upgrading.

MediumCVSS 5.4Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-26207 affects Discourse sites using the discourse-policy plugin. Authenticated users could interact with policy records tied to posts they cannot view, including private categories or private messages, and could infer which post IDs have policies. This is a privacy and integrity issue, not a full system compromise based on the provided sources.

Executive priority

Treat as a timely remediation for Discourse communities using policy workflows, especially where private categories or private messages contain sensitive material. Prioritize upgrade during the next maintenance window; use the documented plugin-disable workaround if upgrade must be delayed.

Technical view

The PolicyController loaded posts by ID without checking whether the current user could see the post. Before patched versions 2025.12.2, 2026.1.1, and 2026.2.0, this missing authorization check allowed unauthorized policy accept/unaccept actions by policy group members and policy presence enumeration by authenticated users. The fix adds a guardian.can_see?(@post) visibility check.

Likely exposure

Exposure is limited to Discourse deployments with the discourse-policy plugin enabled and affected versions installed. Attackers need an authenticated account. Impact is primarily unauthorized policy interaction and limited information disclosure about policy-bearing posts, including content in private areas they cannot otherwise view.

Exploitation context

The CVE record does not indicate CISA KEV listing, and the provided sources do not report active exploitation. The attack is network-accessible, low complexity, requires authentication, and does not require user interaction, according to the supplied CVSS vector.

Researcher notes

This is CWE-862 missing authorization. The issue is not arbitrary post access; it concerns policy actions and policy existence inference through differentiated errors. Evidence is limited to the CVE/GitHub advisory bundle, with no cited proof of exploitation or broader affected products.

Mitigation direction

  • Upgrade Discourse to 2025.12.2, 2026.1.1, 2026.2.0, or later applicable releases.
  • If immediate upgrade is not possible, disable the discourse-policy plugin with policy_enabled = false.
  • Review vendor advisory for version-specific upgrade guidance and operational impact.

Validation and detection

  • Confirm whether the discourse-policy plugin is enabled on each Discourse instance.
  • Inventory Discourse versions and compare against the affected version ranges.
  • Verify the installed version includes the patched post visibility check.
  • Review logs for unusual policy accept or unaccept activity by authenticated users.
Prepared
Confidence
high
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · medium confidence lookup

CWE-862: Authorization and privilege behavior lookup

Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-26207 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.4 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.4CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N2.82.5Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.4Medium
CVSS 3.1 vector shape for CVE-2026-26207Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
discoursediscourse< 2025.12.2, >= 2026.1.0-latest, < 2026.1.1, >= 2026.2.0-latest, < 2026.2.0Listed
Weakness

CWE details

CWE-862

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-862 · source CWE mapping

Missing Authorization

Missing Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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