CVE-2023-4911: GNU C Library Buffer Overflow Vulnerability

How to check if you are exposed to CVE-2023-4911

1. Find every GNU C Library system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
2. Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2023-4911.

US federal agencies had to fix this by 2023-12-12. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Timeline

1. 2023-11-21 · Added to CISA's Known Exploited Vulnerabilities catalog
2. 2023-12-12 · Fix-by date for US federal agencies, passed 1,055 days ago

Vendor advisories and fixes

• https://sourceware.org/git/?p=glibc.git
• https://access.redhat.com/security/cve/cve-2023-4911
• https://www.debian.org/security/2023/dsa-5514

Weakness type

• CWE-122

More exploited GNU vulnerabilities

CISA lists 5 exploited GNU vulnerabilities. The closest matches:

• CVE-2026-24061GNU InetUtils Argument Injection VulnerabilityAdded 2026-01-26
• CVE-2014-6278GNU Bash OS Command Injection VulnerabilityAdded 2025-10-02
• CVE-2014-7169GNU Bourne-Again Shell (Bash) Arbitrary Code Execution VulnerabilityAdded 2022-01-28
• CVE-2014-6271GNU Bourne-Again Shell (Bash) Arbitrary Code Execution VulnerabilityAdded 2022-01-28

Keep going

• All exploited CVEs
• Check another CVE
• What is CISA KEV?
• What is EPSS?

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.