CVE-2023-44487: in the CISA KEV catalogue
HTTP/2 Rapid Reset Attack Vulnerability. CISA added CVE-2023-44487 to the Known Exploited Vulnerabilities catalogue on 2023-10-10 with a default due date of 2023-10-31. Known ransomware campaign use: Unknown. Forensic triage flag: No.
HTTP/2 contains a rapid reset vulnerability that allows for a distributed denial-of-service attack (DDoS). (CISA description)
- Vendor / product
- IETF HTTP/2
- CWE
- CWE-400
- CISA required action
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- EPSS
- 100%, percentile 99 (scored 2026-11-03)
EPSS puts nearly every time in 100 odds (100%) 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-2023-44487 in the CISA KEV catalogue?
Yes. CISA added CVE-2023-44487 (HTTP/2 Rapid Reset Attack Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-10-10. CISA's default due date for it is 2023-10-31.
Is CVE-2023-44487 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2023-44487. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2023-44487?
CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, 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-2023-44487