CVE-2021-43523

In uClibc and uClibc-ng before 1.0.39, incorrect handling of special c ...

Published 10 Nov 2021Modified 17 Jun 2026CWE 79

In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.

Severity by source

NVD9.6CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Trivy's own label is CRITICAL. Rated critical by NVD, CBL-Mariner.

Description

In uClibc and uClibc-ng before 1.0.39, incorrect handling of special characters in domain names returned by DNS servers via gethostbyname, getaddrinfo, gethostbyaddr, and getnameinfo can lead to output of wrong hostnames (leading to domain hijacking) or injection into applications (leading to remote code execution, XSS, applications crashes, etc.). In other words, a validation step, which is expected in any stub resolver, does not occur.

Affected packages and fixed versions

Source	Package	Fixed in
CBL-Mariner 1.0	uclibc-ng	0:1.0.37-2.cm1
CBL-Mariner 2.0	uclibc-ng	0:1.0.37-2.cm2
debian 11	uclibc	no fix listed
debian 12	uclibc	no fix listed
debian 13	uclibc	no fix listed
debian 14	uclibc	no fix listed
echo	uclibc	no fix listed
rapidfort debian 12	uclibc	no fix listed
rapidfort debian 13	uclibc	no fix listed

References

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Vulnerability data compiled from the Trivy vulnerability database (trivy-db, Aqua Security, Apache License 2.0), which aggregates third-party advisories. CVE records are published by The MITRE Corporation under the CVE Terms of Use; CVE is a trademark of MITRE. This product uses data from the NVD API but is not endorsed or certified by the NVD. Severity, titles and advisory data from the GitHub Advisory Database (CC BY 4.0), Red Hat security data (CC BY 4.0) and the other sources linked on each entry. Entries may be summarised or re-formatted; the linked original is the authoritative record.