Race condition in Discourse - #VU165859
Published: November 11, 2026
Vulnerability identifier: #VU165859
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-362
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to claim account privileges associated with an email address they do not own.
The vulnerability exists due to a race condition in Discourse's email-code activation flow when passwordless login or email-code activation is enabled. A remote attacker can exploit an email address swap during activation to gain privileges associated with another email address.
Affected software
Discourse
Remediation
Install security update from vendor's website.
Discourse - addressed in versions 2026.7.5, 2026.9.2, 2026.10.1