CVE-2023-4911: in the CISA KEV catalogue
GNU C Library Buffer Overflow Vulnerability. CISA added CVE-2023-4911 to the Known Exploited Vulnerabilities catalogue on 2023-11-21 with a default due date of 2023-12-12. Known ransomware campaign use: Unknown. Forensic triage flag: No.
GNU C Library's dynamic loader ld.so contains a buffer overflow vulnerability when processing the GLIBC_TUNABLES environment variable, allowing a local attacker to execute code with elevated privileges. (CISA description)
- Vendor / product
- GNU GNU C Library
- CWE
- CWE-122
- CISA required action
- Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- EPSS
- 64%, percentile 99 (scored 2026-11-03)
EPSS puts about 64 in 100 odds (64%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2023-4911 in the CISA KEV catalogue?
Yes. CISA added CVE-2023-4911 (GNU C Library Buffer Overflow Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-11-21. CISA's default due date for it is 2023-12-12.
Is CVE-2023-4911 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2023-4911. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2023-4911?
CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2023-4911