# CVE-2026-55738: Stack Buffer Overflow in rxi/microtar raw_to_header() via non-null-terminated TAR name field

> A stack buffer overflow in the microtar library allows attackers to execute arbitrary code or cause denial of service via crafted TAR files.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 17 Jun 2026
- **Updated:** 10 Aug 2026
- **Also known as:** GHSA-7fm7-h87x-9hjq

## What is CVE-2026-55738?

CVE-2026-55738 is a high-severity memory corruption vulnerability in rxi microtar, published on 17 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A stack-based buffer overflow exists in the raw_to_header function in src/microtar.c in rxi microtar 0.1.0. The function copies the 100-byte name and linkname fields of a TAR header with strcpy without guaranteeing null termination of the source.

Weakness: CWE-170 (Improper Null Termination), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-55738?


## How do I fix CVE-2026-55738?

No fix has been published for CVE-2026-55738 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55738 being exploited?

There is no known exploitation of CVE-2026-55738 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55738 and fix it if it is affected.

What it is: CVE-2026-55738 is a high-severity memory corruption vulnerability in rxi microtar, published on 17 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-55738 in the wild and no public exploit code.

Affected product: rxi microtar. 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-2026-55738/ (Markdown: https://insights.sbomify.com/CVE-2026-55738/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55738
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55738
- OSV: https://osv.dev/vulnerability/CVE-2026-55738

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55738/
Summaries are generated and may contain mistakes; the official description above is the record.