Answer in brief
CVE-2026-91121 records a Medium severity (CVSS 5.0) vulnerability in Discourse: Chat upload filenames rendered as raw HTML in excerpts. The current sources do not mark it as known exploited. The current feed maps discourse/discourse (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps discourse/discourse (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| discourse/discoursegeneric | <2026.8.0 || >=2026.7.0-latest <2026.7.2 || >=2026.6.0-latest <2026.6.3 || >=2026.1.0-latest <2026.1.8 | 2026.8.0, 2026.7.2, 2026.6.3, 2026.1.8 |
Published upstream
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 25, 2026
Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, attacker-controlled upload filenames used in chat message excerpts were rendered as unescaped HTML. A user able to upload a file and send chat content could place markup in a filename that was then interpreted by chat channel lists, chat summary emails, pinned message bars, reply previews, thread previews, and other excerpt renderers. The issue allowed trusted-HTML injection that altered rendered excerpt content, but JavaScript execution was not demonstrated with default Content Security Policy settings. The advisory states that no confidentiality, integrity, or availability impact was identified, while its structured scoring metadata separately assigns low integrity impact. Sites that disable or relax the default CSP have increased exposure. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.
Quoted source text, attributed separately from HOL analysis.