Bug 2344664 (CVE-2025-24032)

Summary: CVE-2025-24032 pam_pkcs11: PAM-PKCS#11 vulnerable to authentication bypass with default value for `cert_policy` (`none`)
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the pam_pkcs11 Linux-PAM login module. If the `cert_policy` is set to none, which is the default value, then pam_pkcs11 will only check if the user is capable of logging into the token. This flaw allows an attacker to create a different token with the user's public data, for example, the user's certificate and a PIN known to the attacker. If no signature with the private key is required, the attacker can log in as a user with that created token.
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Description OSIDB Bzimport 2025-02-10 16:01:05 UTC 
PAM-PKCS#11 is a Linux-PAM login module that allows a X.509 certificate based user login. Prior to version 0.6.13, if cert_policy is set to none (the default value), then pam_pkcs11 will only check if the user is capable of logging into the token. An attacker may create a different token with the user's public data (e.g. the user's certificate) and a PIN known to the attacker. If no signature with the private key is required, then the attacker may now login as user with that created token. The default to *not* check the private key's signature has been changed with commit commi6638576892b59a99389043c90a1e7dd4d783b921, so that all versions starting with pam_pkcs11-0.6.0 should be affected. As a workaround, in `pam_pkcs11.conf`, set at least `cert_policy = signature;`.