# CVE-2026-35366: uutils coreutils printenv inspection evasion via invalid UTF-8 sequences

Source: https://junglewise.ai/threats/cve-2026-35366-uutils-coreutils-printenv-inspection-evasion-via-invalid-utf-8  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-22. Updated: 2026-07-06  
License: CC BY 4.0 with a link back

CVE-2026-35366 · Severity: medium · CVSS 4.4 · Published 2026-04-22

The printenv utility in uutils coreutils, a Rust-based implementation of standard system tools, fails to display environment variables that contain invalid UTF-8 characters. This allows a local attacker to hide malicious environment settings, such as those used to hijack software libraries (LD_PRELOAD), from administrators and security auditing tools. While the system remains functional, security monitoring may fail to detect unauthorized changes to the environment.

Technologies: [Uutils Coreutils](https://junglewise.ai/threats/technologies/uutils-coreutils). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io), [Uutils](https://junglewise.ai/threats/vendors/uutils).

## Quick answers

**Is CVE-2026-35366 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-35366 being exploited in the wild.

**How severe is CVE-2026-35366?** Medium severity, with a CVSS score of 4.4, published 22 April 2026.

**Which products and versions are affected?** uu_printenv (crates.io) < 0.6.0, SEMVER:introduced=0,fixed=0.6.0.

**Is there a fix for CVE-2026-35366?** Yes. uu_printenv (crates.io): upgrade to 0.6.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-35366 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-35366?** Check whether you run uu_printenv (crates.io) or Uutils Coreutils at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- uu_printenv (crates.io): upgrade to 0.6.0 or later

  ```sh
  cargo update -p uu_printenv
  ```


## Technical details

The printenv utility in uutils coreutils (uu_printenv) incorrectly uses Rust's env::var() and env::vars() functions, which silently skip environment variables that are not valid UTF-8. According to POSIX standards, environment variables can contain arbitrary byte sequences. An attacker with local access can craft environment variables (e.g., LD_PRELOAD) containing invalid UTF-8 bytes to ensure they are hidden from administrators or automated security scanners using printenv. This issue was resolved in version 0.6.0 by switching to the _os() variants of the environment functions to handle raw byte sequences.

## Affected products

- uutils coreutils (uu_printenv) < 0.6.0

## Identifiers

- CVE-2026-35366
- GHSA-p7h3-7q52-72w8

## Timeline

- 2025-12-18: disclosed: Issue reported to uutils coreutils maintainers
- 2025-12-22: patched: Fix merged into main branch
- 2026-05-30: advisory: Initial advisory published by maintainers
- 2026-07-06: advisory: GitHub Advisory published

## References

- [https://github.com/uutils/coreutils/security/advisories/GHSA-p7h3-7q52-72w8](https://github.com/uutils/coreutils/security/advisories/GHSA-p7h3-7q52-72w8)
- [https://github.com/uutils/coreutils/issues/9701](https://github.com/uutils/coreutils/issues/9701)
- [https://github.com/uutils/coreutils/pull/9728](https://github.com/uutils/coreutils/pull/9728)
- [https://github.com/uutils/coreutils/commit/0bfbbc00c7895c0fb6ea94987b4aab99e3d7ee52](https://github.com/uutils/coreutils/commit/0bfbbc00c7895c0fb6ea94987b4aab99e3d7ee52)
- [https://github.com/uutils/coreutils/releases/tag/0.6.0](https://github.com/uutils/coreutils/releases/tag/0.6.0)

## Related threats

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