CVE-2021-3639

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-08-22 · updated 2026-06-17
Weakness: CWE-601

Description

A flaw was found in mod_auth_mellon where it does not sanitize logout URLs properly. This issue could be used by an attacker to facilitate phishing attacks by tricking users into visiting a trusted web application URL that redirects to an external and potentially malicious server. The highest threat from this liability is to confidentiality and integrity.

Affected products

uninett mod_auth_mellon: before 0.18.0 — fixed in 0.18.0

How to fix

Upgrade to a fixed version: uninett mod_auth_mellon 0.18.0. Check the vendor advisory for mitigations.

References

https://access.redhat.com/security/cve/CVE-2021-3639
https://bugzilla.redhat.com/show_bug.cgi?id=1980648
https://github.com/latchset/mod_auth_mellon/commit/42a11261b9dad2e48d70bdff7c53dd57a12db6f5
https://access.redhat.com/security/cve/CVE-2021-3639
https://bugzilla.redhat.com/show_bug.cgi?id=1980648
https://github.com/latchset/mod_auth_mellon/commit/42a11261b9dad2e48d70bdff7c53dd57a12db6f5

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