HTTP/2 Rapid Reset Attack Vulnerability

Added to KEV
2023-10-10
Federal due date
2023-10-31
Vendor
IETF
Product
HTTP/2
EPSS
100.0th percentile (score 0.944, as of 2026-06-08)
NVD CVSS v3.1
7.5 (HIGH)
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2023-44487

CISA short description

HTTP/2 contains a rapid reset vulnerability that allows for a distributed denial-of-service attack (DDoS).

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.

NVD description

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.