CVE-2026-91123 Discourse - Open Redirect

Discourse < 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0 contains an open redirect caused by improper handling of backslashes in iframe src traversal guard, letting attackers load unauthorized iframe content, exploit requires crafted iframe source.

CVSS base score 7.2 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.29% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Open Redirect
Impact
Open Redirect, Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Published
24 September 2026
Updated
15 October 2026
Weakness
CWE-22

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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