CVE-2026-35366

Description

The printenv utility in uutils coreutils fails to display environment variables containing invalid UTF-8 byte sequences. While POSIX permits arbitrary bytes in environment strings, the uutils implementation silently skips these entries rather than printing the raw bytes. This vulnerability allows malicious environment variables (e.g., adversarial LD_PRELOAD values) to evade inspection by administrators or security auditing tools, potentially allowing library injection or other environment-based attacks to go undetected.

CVSS v3.1 Score

4.4

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-754 CWE-754

Affected Products

Vendor	Product	Versions
uutils	coreutils	< 0.6.0

References

Advisories & Patches

https://github.com/uutils/coreutils/pull/9728

Exploits

https://github.com/uutils/coreutils/issues/9701 https://github.com/uutils/coreutils/issues/9701

Other References

https://github.com/uutils/coreutils/releases/tag/0.6.0

Frequently Asked Questions

What is CVE-2026-35366? +

The printenv utility in uutils coreutils fails to display environment variables containing invalid UTF-8 byte sequences. While POSIX permits arbitrary bytes in environment strings, the uutils implementation silently skips these entries rather than printing the raw bytes. This vulnerability allows malicious environment variables (e.g., adversarial LD_PRELOAD values) to evade inspection by administrators or security auditing tools, potentially allowing library injection or other environment-based attacks to go undetected. It has a CVSS v3.1 base score of 4.4 (MEDIUM).

How severe is CVE-2026-35366? +

CVE-2026-35366 has a CVSS v3.1 score of 4.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-35366? +

CVE-2026-35366 affects products from uutils, specifically: coreutils. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-35366? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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