Security readout for executives and security teams
Plain-English summary
Discourse has a medium-severity flaw in private message tag filtering. A logged-in user may bypass tag filter conditions and see private message metadata they should not access. The sources do not indicate exposure of message bodies or active exploitation. Organizations using Discourse should prioritize upgrading if private messaging is enabled or sensitive metadata matters.
Executive priority
Treat as a timely patching item, not an emergency based on current evidence. Upgrade affected Discourse systems in the next maintenance window, sooner if private messaging is used for sensitive communications or broad user registration is enabled.
Technical view
CVE-2026-27149 is a CWE-89 SQL injection in Discourse’s `list_private_messages_tag` handling. Before patched releases 2025.12.2, 2026.1.1, and 2026.2.0, the issue can bypass tag filter conditions and potentially disclose unauthorized private message metadata. CVSS v4.0 is 4.9 with network access, low complexity, low privileges, and no user interaction.
Likely exposure
Exposure is limited to affected Discourse deployments before 2025.12.2, 2026.1.1, or 2026.2.0. The attacker needs an account. Risk is higher for forums where private message metadata is sensitive or where many untrusted users can register.
Exploitation context
The source bundle reports no known active exploitation, and the CVSS exploit maturity is unreported. This is not listed as CISA KEV in the provided data. The practical impact described is unauthorized private message metadata disclosure through tag filter bypass, not confirmed full database compromise.
Researcher notes
Evidence is limited to the CVE record and GitHub advisory. The advisory identifies SQL injection in PM tag filtering and patched versions, but the provided data does not include exploit details, indicators of compromise, or workaround guidance.
Mitigation direction
- Upgrade Discourse to 2025.12.2, 2026.1.1, 2026.2.0, or later supported releases.
- Review the Discourse security advisory for deployment-specific update guidance.
- If immediate upgrade is impossible, monitor vendor guidance; sources state no known workarounds.
- Restrict account creation where feasible until patched, especially on sensitive communities.
Validation and detection
- Inventory all Discourse instances and record their exact versions.
- Confirm instances are not running versions listed as affected.
- Verify the security advisory is applied through normal Discourse update channels.
- Review logs for unusual private message tag-filtering activity, if available.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-89: Database access and collection lookup
Injection into data stores can inform collection, data access, and exfiltration detection reviews. 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.
Open ATT&CK lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-27149 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.9 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U
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.
CVSS vector scores
1 official scoreWe 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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
4.9MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/discourse/discourse/security/advisories/GHSA-m6qf-h49w-h38wCVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.