# CVE-2025-71263: Memory corruption in UNIX

> A local buffer overflow in the su command allows attackers to gain root privileges on unsupported UNIX v4 systems.

- **Severity:** High 7.4 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Mar 2026
- **Updated:** 21 Mar 2026
- **Also known as:** GHSA-86j5-wh4f-79gm

## What is CVE-2025-71263?

CVE-2025-71263 is a high-severity memory corruption vulnerability in AT&T Bell Labs UNIX, published on 13 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In UNIX Fourth Research Edition (v4), the su command is vulnerable to a buffer overflow due to the 'password' variable having a fixed size of 100 bytes. A local user can exploit this to gain root privileges. It is unlikely that UNIX v4 is running anywhere outside of a very small number of lab environments. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2025-71263?

It affects 1 product.


Products: Opengroup Unix.

## How do I fix CVE-2025-71263?

No fix has been published for CVE-2025-71263 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-71263 being exploited?

There is no known exploitation of CVE-2025-71263 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71263 and fix it if it is affected.

What it is: CVE-2025-71263 is a high-severity memory corruption vulnerability in AT&T Bell Labs UNIX, published on 13 Mar 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-2025-71263 in the wild and no public exploit code.

Affected product: AT&T Bell Labs UNIX. 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-2025-71263/ (Markdown: https://insights.sbomify.com/CVE-2025-71263/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71263
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71263
- OSV: https://osv.dev/vulnerability/CVE-2025-71263

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From sbomify Insights: https://insights.sbomify.com/CVE-2025-71263/
Summaries are generated and may contain mistakes; the official description above is the record.