# CVE-2026-40553: Stack-based buffer overflow in gawk

> A stack-based buffer overflow in gawk allows attackers to crash the program and potentially execute arbitrary code.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:L/SI:L/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Jul 2026
- **Updated:** 13 Jul 2026
- **Also known as:** AZL-92283, BELL-CVE-2026-40553, DEBIAN-CVE-2026-40553, ECHO-6a06-58a4-e150, GHSA-3j4c-7g5m-7rg5, JLSEC-2026-788, UBUNTU-CVE-2026-40553

## What is CVE-2026-40553?

CVE-2026-40553 is a medium-severity memory corruption vulnerability in GNU gawk, published on 13 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-40553?

It affects 1 product.


Products: Fossies Gawk.

## How do I fix CVE-2026-40553?

Apply the vendor's patch.

## Is CVE-2026-40553 being exploited?

There is no known exploitation of CVE-2026-40553 in the wild and no public exploit code.

## Other vulnerabilities in GNU gawk

- [CVE-2026-40467](https://insights.sbomify.com/CVE-2026-40467/): Use after free in gawk (medium 5.1)
- [CVE-2026-40469](https://insights.sbomify.com/CVE-2026-40469/): Heap buffer overflow in gawk (medium 5.1)
- [CVE-2026-40468](https://insights.sbomify.com/CVE-2026-40468/): Heap buffer overflow in gawk (low 2.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40553 and fix it if it is affected.

What it is: CVE-2026-40553 is a medium-severity memory corruption vulnerability in GNU gawk, published on 13 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40553 in the wild and no public exploit code.

Affected product: GNU gawk. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40553/ (Markdown: https://insights.sbomify.com/CVE-2026-40553/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40553
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40553
- OSV: https://osv.dev/vulnerability/CVE-2026-40553

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40553/
Summaries are generated and may contain mistakes; the official description above is the record.