CVE-2021-22600: in the CISA KEV catalogue
Linux Kernel Privilege Escalation Vulnerability. CISA added CVE-2021-22600 to the Known Exploited Vulnerabilities catalogue on 2022-04-11 with a default due date of 2022-05-02. Known ransomware campaign use: Unknown. Forensic triage flag: No.
Linux Kernel contains a flaw in the packet socket (AF_PACKET) implementation which could lead to incorrectly freeing memory. A local user could exploit this for denial-of-service (DoS) or possibly for privilege escalation. (CISA description)
- Vendor / product
- Linux Kernel
- CWE
- CWE-415
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 6.6%, percentile 93 (scored 2026-11-03)
EPSS puts about 6.6 in 100 odds (6.6%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 93% 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-2021-22600 in the CISA KEV catalogue?
Yes. CISA added CVE-2021-22600 (Linux Kernel Privilege Escalation Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2022-04-11. CISA's default due date for it is 2022-05-02.
Is CVE-2021-22600 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2021-22600. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2021-22600?
CISA's required action: Apply updates per vendor instructions.
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-2021-22600