glibc 2.342.43 DNS hostname violation via gethostbyaddr
CVE-2026-4438 Published on March 20, 2026
gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames
Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library version 2.34 to version 2.43 could result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.
Vulnerability Analysis
Weakness Types
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
What is an Argument Injection Vulnerability?
The software constructs a string for a command to executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
CVE-2026-4438 has been classified to as an Argument Injection vulnerability or weakness.
Products Associated with CVE-2026-4438
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Affected Versions
The GNU C Library glibc:- Version 2.34, <= 2.43 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.