Input validation error in GNU C Library (glibc) - CVE-2026-4438
Published: March 23, 2026
Vulnerability identifier: #VU124258
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-4438
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: GNU
Affected software:
GNU C Library (glibc)
GNU C Library (glibc)
Detailed vulnerability description
The vulnerability allows a remote attacker to perform a spoofing attack.
The vulnerability exists due to insufficient validation when calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library. A remote attacker can force the library to violate the DNS specification and retrieve an invalid DNS hostname to the caller, leading to a potential spoofing attack.
How to mitigate CVE-2026-4438
Install updates from vendor's website.