CVE-2026-54411

Linux-PAM through 1.7.2 contains an observable timing discrepancy (CWE-208) in the pam_userdb module's plaintext-password comparison path in modules/pam_userdb/pam_userdb.c that allows a local or network-adjacent attacker able to repeatedly drive authentication through a calling service to recover the plaintext password of a target account by measuring response-timing differences.

CVSS v3 5.9 MEDIUM

5.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://cwe.mitre.org/data/definitions/208.html
https://github.com/linux-pam/linux-pam
https://github.com/linux-pam/linux-pam/blob/master/libpam/include/pam_inline.h
https://github.com/linux-pam/linux-pam/blob/master/modules/pam_userdb/pam_userdb.c#L327

Configurations

No configuration.

History

No history.

Information

Published : 2026-06-14 18:17

Updated : 2026-08-10 12:17

NVD link : CVE-2026-54411

Mitre link : CVE-2026-54411

CVE.ORG link : CVE-2026-54411

JSON object : View

Products Affected

No product.

CWE

CWE-208

Observable Timing Discrepancy

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La comparaci\u00f3n utiliza strncmp() (o strncasecmp() cuando PAM_ICASE_ARG est\u00e1 configurado) precedida por una verificaci\u00f3n de igualdad de longitud, por lo que el tiempo para rechazar un candidato depende del \u00edndice del primer byte diferente y de si la longitud del candidato coincide con la contrase\u00f1a almacenada, filtrando la longitud de la contrase\u00f1a y los bytes de prefijo individuales. La ruta vulnerable se alcanza cuando el administrador configura pam_userdb con crypt=none, con un m\u00e9todo crypt no reconocido, o sin un argumento crypt=, lo que hace que el m\u00f3dulo almacene y compare credenciales en texto plano."}], "lastModified": "2026-08-10T12:17:17.103", "sourceIdentifier": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c"}