Medium [CVE-2025-5278] heap buffer under-read in gnu coreutils sort via key specification

A flaw was found in GNU Coreutils. The sort utility's begfield() function is vulnerable to a heap buffer under-read.

The program may access memory outside the allocated buffer if a user runs a crafted command using the traditional key format. A malicious input could lead to a crash or leak sensitive data.

The severity of this issue is considered Moderate rather than Critical because successful exploitation requires the use of the traditional key specification syntax with an exceptionally large character position value, which is uncommon in typical usage.

Although the vulnerability can lead to a heap buffer overflow resulting in a read one byte before the allocated buffer, it does not enable code execution, privilege escalation, or direct compromise of data confidentiality or integrity. The impact is therefore primarily limited to potential service disruption due to application crashes.

Furthermore, default RHEL configurations such as SELinux enforcement, ASLR, and memory protections reduce the likelihood of exploitation and limit the scope of any resulting impact. These safeguards, along with typical system usage patterns that do not commonly invoke the vulnerable code path, restrict exploitability in default and hardened environments.