CVE-2026-42512 Remotely triggerable out-of-bounds heap write in dhclient
A heap buffer overflow in FreeBSD's dhclient allows remote attackers to cause a crash or potentially execute arbitrary code via crafted packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-42512?
CVE-2026-42512 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 30 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
As dhclient is building an environment to pass to dhclient-script, it may need to resize the array of string pointers. The code which expands the array incorrectly calculates its new size when requesting memory, resulting in a heap buffer overrun.
A specially crafted packet can cause dhclient to overrun its buffer of environment entries. This can result in a crash, but it may be possible to leverage this bug to achieve remote code execution.
Weakness: CWE-122
Which versions are affected by CVE-2026-42512?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-42512?
No fix has been published for CVE-2026-42512 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-42512 being exploited?
There is no known exploitation of CVE-2026-42512 in the wild and no public exploit code.
Other vulnerabilities in Freebsd Freebsd
Sources
Also known as GHSA-6r9j-w82p-v45p.