GNU gawk patches four memory-corruption flaws
CERT Polska coordinated disclosure of four gawk vulnerabilities, including a possible code-execution bug, fixed in gawk 5.4.1.
CERT Polska coordinated the disclosure of four vulnerabilities in GNU gawk, a widely used text-processing utility on Unix-like systems. The flaws include a use-after-free in io.c's do_getline_redir() routine (CVE-2026-40467) that can crash the program, two integer overflow issues in builtin.c (CVE-2026-40468 and CVE-2026-40469) that can lead to memory exhaustion or corruption of heap metadata, and a buffer overflow in extension/readdir.c's ftype() routine (CVE-2026-40553) that could potentially allow code execution, though this has not been confirmed as feasible.
All four issues were reported responsibly by researchers Michał Majchrowicz and Marcin Wyczechowski of AFINE, and have been fixed in gawk release 5.4.1. There is no indication of active exploitation; the vulnerabilities are disclosed as part of a standard coordinated vulnerability disclosure process. Organizations running gawk, particularly on systems processing untrusted input or 32-bit builds (relevant to CVE-2026-40469), should update to the patched version.
Mentioned in this report
Source reporting: https://cert.pl/en/posts/2026/07/CVE-2026-40467
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