Discourse
CVE-2026-33426
LOW
Severity by source
AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N
Lifecycle Timeline
2DescriptionGitHub Advisory
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, users with tag-editing permissions could edit and create synonyms for tags hidden in restricted tag groups, even if they lacked visibility into those tags. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.
AnalysisAI
Discourse versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain an authorization bypass vulnerability where users with tag-editing permissions can edit and create tag synonyms for tags within restricted tag groups, even when those users lack visibility into the restricted tags themselves. This represents a broken access control issue (CWE-862) with low CVSS score (3.5) due to high privilege requirement and limited impact scope, though it enables unauthorized information disclosure and tag manipulation within the platform. …
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Vulnerability AssessmentAI
| Risk Assessment | While the CVSS v3.1 base score is 3.5 (low), the risk profile presents nuance. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A moderator with tag-editing permissions but intentionally restricted from viewing sensitive topic tags (e.g., internal security issues or private support channels) leverages the vulnerability to create synonyms for those hidden tags, effectively revealing their existence and allowing tag-based topic discovery without proper authorization. Since the attack requires high privileges and user interaction (network-based but requires an authenticated session), exploitation is limited to insider threats or compromised moderator accounts; however, the low complexity (AC:L) means the attacker needs only basic familiarity with the tag management interface to succeed. |
| Remediation | Upgrade Discourse immediately to version 2026.1.2, 2026.2.1, or 2026.3.0-latest.1 or later, depending on your current release branch. … Detailed patch versions, workarounds, and compensating controls in full report. |
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During next maintenance window: Apply vendor patches when convenient. …
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External POC / Exploit Code
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