# CVE-2026-18739: Popt-devel: popt-static: off-by-one in poptstuffargs

> A local attacker can exploit an off-by-one error in the popt library to corrupt memory and potentially execute arbitrary code.

- **Severity:** Low 2.5 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** AZL-94508, AZL-94596, BELL-CVE-2026-18739, DEBIAN-CVE-2026-18739, ECHO-784f-603d-c633, GHSA-255r-gqmx-m2jm, OESA-2026-3611, OESA-2026-3612, OESA-2026-3613, OESA-2026-3614, UBUNTU-CVE-2026-18739

## What is CVE-2026-18739?

CVE-2026-18739 is a low-severity memory corruption vulnerability in Red Hat Enterprise Linux 10, published on 4 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in popt, a command-line option parsing library. An off-by-one error in the poptStuffArgs function, when repeatedly called by a host application or through deep alias nesting, can lead to corruption of internal program data. This corruption could potentially enable a local attacker to execute arbitrary code if the host application then unsafely processes the altered data.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-18739?


## How do I fix CVE-2026-18739?

Apply the vendor's patch.

## Is CVE-2026-18739 being exploited?

There is no known exploitation of CVE-2026-18739 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18739 and fix it if it is affected.

What it is: CVE-2026-18739 is a low-severity memory corruption vulnerability in Red Hat Enterprise Linux 10, published on 4 Aug 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-2026-18739 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. 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-2026-18739/ (Markdown: https://insights.sbomify.com/CVE-2026-18739/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18739
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18739
- OSV: https://osv.dev/vulnerability/CVE-2026-18739

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18739/
Summaries are generated and may contain mistakes; the official description above is the record.