# CVE-2026-35355: uutils coreutils install Arbitrary File Overwrite via Symlink TOCTOU Race

> A local attacker can exploit a TOCTOU race condition in the install utility to overwrite arbitrary system files via symlink manipulation, leading to privilege escalation.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **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:** 22 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-35355, GHSA-239g-2685-54x3, UBUNTU-CVE-2026-35355

## What is CVE-2026-35355?

CVE-2026-35355 is a medium-severity vulnerability in Uutils coreutils, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The install utility in uutils coreutils is vulnerable to a Time-of-Check to Time-of-Use (TOCTOU) race condition during file installation. The implementation unlinks an existing destination file and then recreates it using a path-based operation without the O_EXCL flag. A local attacker can exploit the window between the unlink and the subsequent creation to swap the path with a symbolic link, allowing them to redirect privileged writes to overwrite arbitrary system files.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-35355?

2 open source packages ship an affected version, including uu_install. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `uu_install` | crates.io | All versions | 0.6.0 |
| `uu_install` | crates.io | All versions | 0.6.0 |

Products: Uutils Coreutils.

## How do I fix CVE-2026-35355?

Upgrade uu_install to 0.6.0 or later.

## Is CVE-2026-35355 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35355 exists.

## Other vulnerabilities in Uutils coreutils

- [CVE-2026-35338](https://insights.sbomify.com/CVE-2026-35338/): uutils coreutils chmod Path Traversal Bypass of --preserve-root (high 7.3)
- [CVE-2026-35368](https://insights.sbomify.com/CVE-2026-35368/): uutils coreutils chroot Local Privilege Escalation and chroot Escape in via Name Service Switch (NSS) Injection (high 7.2)
- [CVE-2026-35341](https://insights.sbomify.com/CVE-2026-35341/): uutils coreutils mkfifo Unauthorized Permission Change on Existing Files (high 7.1)
- [CVE-2026-35352](https://insights.sbomify.com/CVE-2026-35352/): uutils coreutils mkfifo Privilege Escalation via TOCTOU Race Condition (high 7.0)
- [CVE-2026-35349](https://insights.sbomify.com/CVE-2026-35349/): uutils coreutils Path-Based Safety Bypass with --preserve-root (medium 6.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-35355 and fix it if it is affected.

What it is: CVE-2026-35355 is a medium-severity vulnerability in Uutils coreutils, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35355 exists.

Affected packages and fixed versions:
- uu_install (crates.io): affected all versions; fixed in 0.6.0
- uu_install (crates.io): affected all versions; fixed in 0.6.0

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-2026-35355/ (Markdown: https://insights.sbomify.com/CVE-2026-35355/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35355
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35355
- OSV: https://osv.dev/vulnerability/CVE-2026-35355

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-35355/
Summaries are generated and may contain mistakes; the official description above is the record.