CVE-2021-43523: 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.

Overview

Severity: Critical (CVSS 9.6)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Exploit Status: Not Exploited
Patch Tuesday: 2021-Nov
Released: 2021-11-18
Last Updated: 2021-12-16
EPSS Score: 3.82% (percentile: 88.1%)

FAQ

Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability? One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.

Overview

FAQ

Affected Products (2)

Other

Revision History