CVE-2026-19542: 
Wolfi vulnerability analysis and mitigation

CVE-2026-19542 is an out-of-bounds array write vulnerability in the GNU C Library (glibc) tdelete function, caused by incorrect management of array sizes leading to memory corruption. It affects glibc across multiple Linux distributions, including Ubuntu 22.04 LTS, 24.04 LTS, and 26.04 LTS. The vulnerability was reported on August 25, 2026, and patches were made available shortly thereafter. It carries a CVSS v3.1 base score of 4.2 (Medium), requiring local access, low privileges, and user interaction to exploit (Red Hat Advisory, Red Hat Bugzilla).

The root cause is classified as CWE-787 (Out-of-bounds Write): the tdelete function in glibc incorrectly manages array sizes, using alloca-based dynamic stack allocation that can be exceeded, resulting in out-of-bounds stack array accesses and memory corruption. The fix allocates maximum array sizes directly upfront, eliminating alloca usage and adding assertion guards to prevent regression if tree balancing logic changes. Exploitation requires local access with low privileges and user interaction, making it a relatively constrained attack vector (Red Hat Bugzilla, Ubuntu USN-8737-1).

Successful exploitation can lead to denial of service or disclosure of sensitive information from process memory, and Ubuntu's advisory additionally notes the potential for arbitrary code execution. Because tdelete is part of the widely deployed GNU C Library, any application on an affected system that uses binary search tree deletion operations could be impacted. The scope is limited to the local system (unchanged scope), with low impacts to confidentiality, integrity, and availability (Red Hat Advisory, Ubuntu USN-8737-1).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation as of the time of reporting. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Detection coverage exists via Nessus plugin 339040. The high attack complexity and requirement for user interaction further reduce practical exploitability (Red Hat Advisory, Tenable Nessus).

Vendors have released patched glibc packages addressing this vulnerability. Ubuntu users should update to the following versions: Ubuntu 26.04 LTS — libc6 2.43-2ubuntu2.4; Ubuntu 24.04 LTS — libc6 2.39-0ubuntu8.9; Ubuntu 22.04 LTS — libc6 2.35-0ubuntu3.15. A standard system update (apt upgrade) will apply the necessary changes. Red Hat has also issued a patch tracked under Bugzilla #2523249; users of Red Hat-based distributions should apply available updates promptly, prioritizing systems where low-privileged local users have interactive access (Ubuntu USN-8737-1, Ubuntu USN-8737-2, Red Hat Bugzilla).