synced 11 MIN AGO
01 Record

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

CriticalPUBLISHEDCNA: mitre
CNA base score9.6 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

02 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

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
3.07% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 87.4% of scored records. A rank, not a probability.
NVD base score
9.6 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2021-11-10 14:03Z4 YR AGO
Last updated
2025-05-05 16:46Z1 YR AGO
Reserved
2021-11-08
Assigning CNA
mitre
Record state
PUBLISHED
Severity
Critical (CVSS 9.6)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weaknesses
  • CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Base
Data version
5.1
Document digest
71aee2abfd8e471e7e1a787fa0582abad625ffcc04fb28a9cd140dc68c17dbc5

05 Affected products

VendorProductVersionsPlatforms
uclibcuclibcNot specified—
uclibc-ng_projectuclibc-ngNot specified—

06 References

07 Fixed in

Debian 12

  • uclibc
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • uclibc
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • uclibc
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.