CVE-2026-0861

A flaw was found in the glibc library. Passing an excessively large alignment value to the memalign suite of functions, such as memalign, posix_memalign, aligned_alloc, valloc and pvalloc, an integer overflow can occur during internal size calculations due to improper overflow checks, causing an allocation of a small chunk of memory which is subsequently used for writing. This issue can result in an application crash or heap memory corruption.

To exploit this flaw, an attacker needs to find an application linked to the glibc library that is using one of the vulnerable functions (memalign, posix_memalign, aligned_alloc, valloc or pvalloc) in a way that the alignment parameter can be user-controlled, allowing an attacker to trigger the integer overflow. However, the alignment parameter used by the functions is usually hard-coded power of two and do not allow arbitrary values, specially values supplied by a user. There is no known application vulnerable to this issue.

Also, default Red Hat Enterprise Linux security features, including SELinux enforcement, Address Space Layout Randomization (ASLR) and memory protections significantly increase the difficult of achieving arbitrary code execution, limiting the impact of this vulnerability.

Due to these reasons, this vulnerability has been rated with a low severity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Applications calling one of the vulnerable functions and allowing the alignment parameter to be set by user-controlled input can implement additional validations checks, ensuring the alignment value is a power of two and does not exceed a sane limit, for example the system page size or a maximum of 64KB. This prevents the excessively large value required to trigger the integer overflow.