Home/CVE/In uClibc and uClibc-ng before 1.0.39, incorrect handling of special characters in domain names returned by DNS servers
CVE

CVE-2021-43523

In uClibc and uClibc-ng before 1.0.39, incorrect handling of special characters in domain names returned by DNS servers

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.

CRITICAL · CVSS 9.6 EPSS 0.02885
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

2
uclibc<= 0.9.33.2
uclibc-ng project uclibc-ng< 1.0.39
▣

Scoring & Timeline

9.6
CRITICAL · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD10 Nov 2021 · 03:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
msrcCVE-2021-43523
cisa-csafcisa-csaf-csaf_files-OT-white-2023-icsa-23-234-01
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/wbx-github/uclibc-ng/commit/0f822af0445e5348ce7b7bd8ce1204244f31d174PatchThird Party Advisory
https://uclibc-ng.org/Vendor Advisory
https://www.openwall.com/lists/oss-security/2021/11/09/1ExploitMailing ListThird Party Advisory
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