CVE-2026-0861 — Integer overflow in memalign leads to heap corruption

Affected: The GNU C Library glibc

Passing too large an alignment to the memalign suite of functions (memalign, posix_memalign, aligned_alloc) in the GNU C Library version 2.30 to 2.42 may result in an integer overflow, which could consequently result in a heap corruption.

Note that the attacker must have control over both, the size as well as the alignment arguments of the memalign function to be able to exploit this. The size parameter must be close enough to PTRDIFF_MAX so as to overflow size_t along with the large alignment argument. This limits the malicious inputs for the alignment for memalign to the range [1<<62+ 1, 1<<63] and exactly 1<<63 for posix_memalign and aligned_alloc.

Typically the alignment argument passed to such functions is a known constrained quantity (e.g. page size, block size, struct sizes) and is not attacker controlled, because of which this may not be easily exploitable in practice. An application bug could potentially result in the input alignment being too large, e.g. due to a different buffer overflow or integer overflow in the application or its dependent libraries, but that is again an uncommon usage pattern given typical sources of alignments.

USN-8005-1 — glibc vulnerabilities

Affected: Ubuntu:Pro:16.04:LTS: glibc, Ubuntu:Pro:18.04:LTS: glibc, Ubuntu:Pro:20.04:LTS: glibc, Ubuntu:22.04:LTS: glibc, Ubuntu:24.04:LTS: glibc, Ubuntu:25.10: glibc

Vitaly Simonovich discovered that the GNU C Library did not properly initialize the input when WRDE_REUSE is used. An attacker could possibly use this issue to cause applications to crash, leading to a denial of service. (CVE-2025-15281)

Anastasia Belova discovered that the GNU C Library incorrectly handled the regcomp function when memory allocation failures occured. An attacker could possibly use this issue to cause applications to crash, leading to a denial of service, or possibly execute arbitrary code. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2025-8058)

Igor Morgenstern discovered that the GNU C Library incorrectly handled the memalign function when doing memory allocation. An attacker could possibly use this issue to cause applications to crash, leading to a denial of service, or possibly execute arbitrary code. This issue only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS and Ubuntu 25.10. (CVE-2026-0861)

Igor Morgenstern discovered that the GNU C Library incorrectly handled certain DNS backend when queries for a zero-valued network. An attacker could possibly use this issue to cause a denial of service or obtain sensitive information. (CVE-2026-0915)

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CVE-2026-0861 — Integer overflow in memalign leads to heap corruption

USN-8005-1 — glibc vulnerabilities