What’s Vulnerable › Vulnerabilities

CVE-2026-49256: Discourse: Hidden tag names leaked via category serializers

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-09 · updated 2026-07-14
• Weakness: CWE-200

Description

Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups could leak to anonymous and unauthorized users through category and group endpoints. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.

Affected products

• discourse: from 2026.1.0 before 2026.1.5; from 2026.4.0 before 2026.4.2; from 2026.5.0 before 2026.5.1; 2026.6.0 — fixed in 2026.1.5, 2026.4.2, 2026.5.1

How to fix

Upgrade to a fixed version: discourse 2026.1.5, 2026.4.2, 2026.5.1. Check the vendor advisory for mitigations.

References

• https://github.com/discourse/discourse/releases/tag/v2026.1.5
• https://github.com/discourse/discourse/releases/tag/v2026.4.2
• https://github.com/discourse/discourse/releases/tag/v2026.5.1
• https://github.com/discourse/discourse/releases/tag/v2026.6.0
• https://github.com/discourse/discourse/security/advisories/GHSA-mwp7-572g-6qpx

Get alerted when CVE-2026-49256 or the next vulnerability affects your stack