CVE-2026-42511

HIGH

Published Apr 30, 2026 Modified May 1, 2026 CWE-149

Description

The BOOTP file field is written to the lease file without escaping embedded double-quotes, allowing injection of arbitrary dhclient.conf directives. When the lease file is subsequently re-parsed by dhclient, e.g., after a system restart, an attacker-controlled field from the lease is passed to dhclient-script(8), which evaluates it. A rogue DHCP server may be able to execute arbirary code as root on a system running dhclient.

CVSS v3.1 Score

8.1

HIGH

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

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.11%

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-149 CWE-149

Affected Products

Vendor	Product	Versions
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All
freebsd	freebsd	All

References

Advisories & Patches

https://security.freebsd.org/advisories/FreeBSD-SA-26:12.dhclient.asc

Frequently Asked Questions

What is CVE-2026-42511? +

How severe is CVE-2026-42511? +

CVE-2026-42511 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42511? +

CVE-2026-42511 affects products from freebsd, specifically: freebsd. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42511? +

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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