CVE-2023-44487
High 7.5 Exploited in the wild (KEV)
Confirmed active exploitation — CISA KEV catalog
- Name
- HTTP/2 Rapid Reset Attack Vulnerability
- Added to catalog
- Remediation due date (US federal)
- 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.
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.
Metrics
- CVSS 3.1
-
7.5 (HIGH)
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 100% (percentile: 100) as of 2 November 2026
- CWE
- CWE-400
Affected products
siemens: simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware; siemens: simatic s7-1500 cpu 1518f-4 pn\/dp mfp; siemens: sinec ins; siemens: sinec nms; siemens: st7 scadaconnect; siemens: ruggedcom ape1808 firmware; siemens: ruggedcom ape1808; siemens: simatic s7-1500 cpu 1518-4 pn\/dp mfp firmware; siemens: simatic s7-1500 cpu 1518-4 pn\/dp; siemens: siplus s7-1500 cpu 1518-4 pn\/dp mfp firmware; siemens: siplus s7-1500 cpu 1518-4 pn\/dp mfp; ietf: http; nghttp2: nghttp2; netty: netty; envoyproxy: envoy
References
- https://access.redhat.com/security/cve/cve-2023-44487 Vendor Advisory
- https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/ Technical DescriptionVendor Advisory
- https://blog.cloudflare.com/zero-day-rapid-reset-http2-record-breaking-ddos-att… Third Party AdvisoryVendor Advisory
- https://blog.litespeedtech.com/2023/10/11/rapid-reset-http-2-vulnerablilty/ Vendor Advisory
- https://blog.vespa.ai/cve-2023-44487/ Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2242803 Issue TrackingVendor Advisory
- https://bugzilla.suse.com/show_bug.cgi?id=1216123 Issue TrackingVendor Advisory
- https://cgit.freebsd.org/ports/commit/?id=c64c329c2c1752f46b73e3e6ce9f4329be662… Mailing ListPatchVendor Advisory
- https://cloud.google.com/blog/products/identity-security/google-cloud-mitigated… Technical DescriptionVendor Advisory
- https://cloud.google.com/blog/products/identity-security/how-it-works-the-novel… Technical DescriptionVendor Advisory