CVE-2026-40553 in GNU awk
Buffer overflow vulnerability has been found in "extension/readdir.c" program file of gawk (ftype() routine). This issue could be used to crash the program and potentially to achieve code execution, although the latter has not been confirmed to be feasible. It affects gawk in versions 5.4.0 and below.
Quick answer
GNU awk should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- GNU awk 5.4.0 and earlier
Fixed versions
- GNU awk 5.4.1 or later
How to fix it
CVE-2026-40553 affects GNU awk. In simple terms, an attacker may be able to misuse the affected system if it is exposed or if a user opens unsafe input. Update to GNU awk 5.4.1 or later. If you cannot update right away, limit access until the fix is installed.
- Find every place where GNU awk is installed or used.
- Check the installed version against the affected versions on this page.
- Update to GNU awk 5.4.1 or later.
- If an update is not possible today, turn off the risky feature or restrict it to trusted users only.
- Review recent logs for strange access, failed logins, changed files, or unexpected admin actions.
- Rotate passwords, API keys, and tokens if you think the system may have been abused.
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Verify the fix
- Confirm GNU awk now runs a fixed version or has the vendor mitigation in place.
- Test the affected feature again and make sure normal users can still work.
- Check that public or untrusted access is blocked where it should be blocked.
- Review logs again after the fix and confirm the same suspicious activity does not continue.
- Run a new Fixnx scan or your normal security check and save the result.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-40553?
GNU awk versions listed as affected should be reviewed: GNU awk 5.4.0 and earlier.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.