CVE-2025-0395

What it actually does

The assert() function in glibc 2.13-2.40 fails to allocate enough space for the assertion failure message string and size information, causing a buffer overflow when the message size is page-aligned.

Why it matters to the business

Services built on older Red Hat Enterprise Linux 6 systems using Samba packages may experience unexpected crashes and loss of availability when assertion failures occur under specific message-size conditions.

How an attack unfolds

A local attacker triggers an assertion failure in a process linked against the vulnerable glibc by supplying input that produces a page-aligned assertion message, resulting in memory corruption that manifests as a denial-of-service condition.

How to fix it

Upgrade all listed samba4 packages on Red Hat Enterprise Linux 6 client and computenode variants to version 0:4.2.10-7.el6_8 or later.

How to confirm the fix worked

Confirm installed package versions meet or exceed the listed fixed releases and verify that assertion-failure paths no longer produce crashes under page-aligned message conditions.

Typical attack path

1. Obtain local access to a system running affected Samba packages on RHEL 6
2. Identify or induce an assertion failure whose message length aligns to a page boundary
3. Trigger the flawed assert path to produce the buffer overflow and crash the process

How to detect it

Examine system and application logs for segmentation faults or abrupt process terminations that coincide with assertion messages; correlate with processes linked to the vulnerable glibc versions.

What your security team should do

• Apply the specified samba4 package updates immediately on all RHEL 6 systems
• Scan for and remove any remaining vulnerable package versions
• Review application code for production use of assert() and replace with proper error handling