CVE-2013-7322 in OATH Toolkit
Summary
by MITRE
usersfile.c in liboath in OATH Toolkit before 2.4.1 does not properly handle lines containing an invalid one-time-password (OTP) type and a user name in /etc/users.oath, which causes the wrong line to be updated when invalidating an OTP and allows context-dependent attackers to conduct replay attacks, as demonstrated by a commented out line when using libpam-oath.
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Analysis
by VulDB Data Team • 05/07/2026
The vulnerability described in CVE-2013-7322 resides within the liboath library component of the OATH Toolkit software suite, specifically in the usersfile.c module. This flaw affects versions prior to 2.4.1 and represents a critical security weakness in the handling of authentication tokens within the /etc/users.oath configuration file. The issue manifests when the system encounters lines containing invalid one-time-password OTP types alongside user names, creating a scenario where the library fails to properly process these malformed entries during OTP invalidation procedures.
The technical implementation flaw stems from inadequate input validation and parsing logic within the usersfile.c module. When processing the /etc/users.oath file, the library does not correctly distinguish between valid and invalid OTP type entries, particularly when dealing with commented-out lines or malformed data. This improper handling causes the system to update incorrect lines during OTP invalidation operations, fundamentally undermining the integrity of the authentication process. The vulnerability operates at the intersection of configuration file parsing and authentication token management, creating a path for malicious actors to exploit the system's failure to properly validate input data.
The operational impact of this vulnerability extends beyond simple authentication failures, creating conditions that enable sophisticated replay attacks. Attackers can exploit the improper line handling to manipulate the OTP invalidation process, effectively bypassing security controls that should prevent reuse of previously issued tokens. This weakness is particularly dangerous when combined with the libpam-oath module, which serves as the Pluggable Authentication Module interface for OATH-based authentication systems. The vulnerability allows context-dependent attackers to conduct replay attacks by leveraging the library's failure to properly update the correct entries in the users.oath file, potentially enabling unauthorized access to protected systems.
The security implications of this vulnerability align with CWE-20, which addresses improper input validation, and can be mapped to ATT&CK technique T1555.004 related to credentials from password stores. The flaw creates a persistent security weakness that can be exploited across multiple authentication contexts, as the compromised OTP invalidation mechanism affects the entire authentication flow. Organizations utilizing OATH-based authentication systems are particularly vulnerable, as the issue impacts the fundamental security guarantees provided by one-time password mechanisms. The vulnerability demonstrates the critical importance of proper input validation in security-critical components, where malformed data can lead to complete bypass of authentication controls.
Mitigation strategies should focus on immediate patching of the OATH Toolkit to version 2.4.1 or later, which contains the necessary fixes for the usersfile.c parsing logic. System administrators should also implement monitoring of the /etc/users.oath file for malformed entries and establish procedures for regular validation of authentication configuration files. Additional protective measures include implementing strict input validation at the application level, deploying intrusion detection systems to monitor for unauthorized authentication attempts, and conducting regular security audits of authentication infrastructure. The vulnerability highlights the necessity of robust error handling and input validation in security-critical libraries, emphasizing that even seemingly minor parsing flaws can have significant security implications.