Vulnerability record · CVE-2021-43523 · published 10 November 2021

CVE-2021-43523: Uclibc cross-site scripting vulnerability

Uclibc · Uclibc

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.

9.6 CVSS 3.1 Critical EPSS 3.1% · top 12.9% CWE-79 · Cross-site scripting

9.6CVSS 3.1 base score, v2 6.8

3.1%EPSS exploitation probability, 30 days

NoNot in CISA KEV

2Affected product versions listed by NVD

6References, 2 tagged exploit

17 Jun 2026Last modified by NVD

Description

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Uclibc Uclibc UUclibc Ng Uclibc Ng Project

References

Link	Tags
https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174	PatchThird Party Advisory
https://uclibc-ng.org/	Vendor Advisory
https://www.openwall.com/lists/oss-security/2021/11/09/1	ExploitMailing ListThird Party Advisory
https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174	PatchThird Party Advisory
https://uclibc-ng.org/	Vendor Advisory
https://www.openwall.com/lists/oss-security/2021/11/09/1	ExploitMailing ListThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-43523), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.