---
cve: "CVE-2026-91123"
severity: "HIGH"
cvss: 7.2
epss: ""
vendor: "discourse"
kev: false
exploited: false
published: "2026-09-24 17:17:08"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-27T12:58:30+02:00"
---

# CVE-2026-91123

> 7.2 HIGH · 🧪 PoC

## Beschreibung

Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allowed_iframes subpath check while browser URL normalization moved the iframe outside the intended allowed path. The resulting iframe could load content from a location that the administrator did not allow. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- fb9247e04a826ab8e4d91168b3c4c839ec40bccc (Commit)
- 3ab62a8397926ed934b667a5db06284c45b4c774 (Commit)

## Referenzen

- <https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc>
- <https://github.com/discourse/discourse/pull/42882>
- <https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318>
- <https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24>
- <https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be>
- <https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-91123) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_