Overview
CVE-2025-14104 is a medium severity vulnerability found in util-linux, specifically affecting the setpwnam() function. This flaw allows for a heap buffer overread when processing usernames that are 256 bytes in length. The vulnerability primarily impacts SUID (Set User ID) login-utils utilities that write to the password database. Successful exploitation could potentially lead to information disclosure, denial of service, or, in more severe scenarios, privilege escalation.
Technical Details
The vulnerability resides in the way setpwnam(), a function used to retrieve user account information by username, handles unusually long usernames. When a username with a length of 256 bytes is processed, a heap buffer overread can occur during memory operations. This occurs because setpwnam() and related functions may not adequately validate the length of the username before copying it into a buffer. Because `util-linux` provides core tools for managing users and the system, problems in it can create a variety of security problems.
The overread occurs because the code attempts to read beyond the allocated buffer when processing these extended usernames, potentially exposing sensitive data residing in adjacent memory regions. Specifically, SUID binaries relying on `setpwnam()` to update the password database are at risk, as an attacker-controlled username could trigger the overread.
Example vulnerable code snippet (illustrative):
// Simplified example - actual code will be more complex
char username[256];
strncpy(username, attacker_provided_username, 256); // Possible overread if attacker_provided_username > 255
// Further processing of username
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-14104 is 6.1 (Medium).
The CVSS vector string is not available for this hypothetical CVE but would likely consider factors like attack vector, attack complexity, privileges required, user interaction, scope, confidentiality impact, integrity impact, and availability impact.
Possible Impact
The exploitation of CVE-2025-14104 can have several potential impacts:
- Information Disclosure: The heap buffer overread could expose sensitive data stored in memory adjacent to the affected buffer. This data might include passwords, cryptographic keys, or other confidential information.
- Denial of Service (DoS): By triggering the overread, an attacker could potentially cause the affected utility to crash, leading to a denial of service.
- Privilege Escalation: In the context of SUID utilities, a successful exploitation could lead to privilege escalation, allowing an attacker to execute commands with elevated privileges.
Mitigation and Patch Steps
The primary mitigation strategy is to apply the official patch provided by the util-linux developers. Here are the recommended steps:
- Monitor for Updates: Stay informed about security updates and patches released by your Linux distribution or the util-linux project.
- Apply Patches: As soon as a patch addressing CVE-2025-14104 is available, apply it to your systems. This typically involves updating the util-linux package.
- Workarounds (if no patch is immediately available):
- Implement input validation to restrict the length of usernames accepted by applications using
setpwnam()to less than 256 bytes.
- Implement input validation to restrict the length of usernames accepted by applications using
- Code Review: If you are developing applications that use
setpwnam(), review your code to ensure proper input validation and buffer handling.
