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CVE-2026-49256 discourse CVE debrief

CVE-2026-49256 is a vulnerability in Discourse, an open-source discussion platform. Prior to versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, restricted tag and tag-group names attached to publicly readable categories could leak to anonymous and unauthorized users. This issue has been fixed in the mentioned versions. The vulnerability involves restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups. These could leak to anonymous and unauthorized users through category and group endpoints.

Vendor
discourse
Product
Unknown
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-09
Original CVE updated
2026-07-10
Advisory published
2026-07-09
Advisory updated
2026-07-10

Who should care

Users of Discourse, especially those with publicly readable categories, should be aware of this vulnerability and ensure they are running a patched version of the software. Affected operator, platform, vulnerability-management, and security-team impact should be reviewed.

Technical summary

The vulnerability involves restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups. These could leak to anonymous and unauthorized users through category and group endpoints. The issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5. Affected product deployments should be reviewed for exposure and updated to a patched version.

Defensive priority

Medium priority due to the potential for information leakage.

Recommended defensive actions

  • Inventory and update Discourse installations to versions 2026.6.0, 2026.5.1, 2026.4.2, or 2026.1.5.
  • Review category and group endpoint permissions.
  • Monitor for unusual activity related to tag and tag-group names.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
  • Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
  • Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record was published on 2026-07-09T22:17:05.260Z and was last modified on 2026-07-10T14:16:53.577Z. The NVD entry is currently being reviewed. Evidence limits suggest that further verification is needed to confirm affected scope and severity. Defenders should verify the official advisory and CVE record for accurate information.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-49256 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-49256

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-49256 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-49256

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.