CVE-2026-91123EPSS p19.3%

CVE-2026-91123CVE-2026-91123

Description

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.

Scoring

CVSS 7.2 ()
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
EPSS0.29% probability of exploitation · percentile 19.3% · 2026-10-05T12:00:23Z
Last modified2026-09-24
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.