What’s Vulnerable › Vulnerabilities
CVE-2021-43523
- Severity: critical (CVSS 9.6 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 3.1% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2021-11-10 · updated 2026-06-17
- Weakness: CWE-79
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 products
How to fix
Upgrade to a fixed version: uClibC-ng 1.0.39. Check the vendor advisory for mitigations.
References
- https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174
- https://uclibc-ng.org/
- https://www.openwall.com/lists/oss-security/2021/11/09/1
- https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174
- https://uclibc-ng.org/
- https://www.openwall.com/lists/oss-security/2021/11/09/1
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