CVE-2026-91122 Discourse - Stored XSS

Discourse < 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0 contains a stored XSS caused by crafted HTML in the video placeholder component allowing attribute breakout and event handler injection, letting authenticated users with default trust-level execute arbitrary JavaScript in other users' sessions, exploit requires authenticated user with posting privileges.

CVSS base score 8.7 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
EPSS
0.26% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Stored XSS
Impact
Client Script Exec, Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Published
24 September 2026
Updated
15 October 2026
Weakness
CWE-79

Vendor fix

Update to versions 2026.1.8, 2026.6.3, 2026.7.2, or 2026.8.0.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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