CVE-2023-44487HTTP/2 Rapid Reset Attack Vulnerability

BOD 26-04 remediation window

With CISA's SSVC answers for this CVE (automatable: yes, technical impact: partial), BOD 26-04 Table 1 gives 3 days on a publicly exposed asset (row 2) and 14 days on an asset that is not publicly exposed (row 10) ^S06. The catalogue due date, 21 days after the date added, was set before BOD 26-04 took effect on 10 June 2026 ^S06. The directive binds US federal civilian executive branch agencies only.

What CISA says

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.

Notes

This vulnerability affects a common open-source component, third-party library, or protocol used by different products. For more information, please see: HTTP/2 Rapid Reset Vulnerability, CVE-2023-44487 | CISA: https://www.cisa.gov/news-events/alerts/2023/10/10/http2-rapid-reset-vulnerability-cve-2023-44487; https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/; https://nvd.nist.gov/vuln/detail/CVE-2023-44487

CWE in the catalogue

CWE-400

Official links

• CISA KEV catalogue entry cisa.gov
• NVD record nvd.nist.gov

Vendor advisory and patch links

References NVD tags Vendor Advisory or Patch, exactly as NVD lists them.

• https://access.redhat.com/security/cve/cve-2023-44487 Vendor Advisory
• https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/ Technical Description, Vendor Advisory
• https://blog.cloudflare.com/zero-day-rapid-reset-http2-record-breaking-ddos-attack/ Third Party Advisory, Vendor 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 Tracking, Vendor Advisory
• https://bugzilla.suse.com/show_bug.cgi?id=1216123 Issue Tracking, Vendor Advisory
• https://cgit.freebsd.org/ports/commit/?id=c64c329c2c1752f46b73e3e6ce9f4329be6629f9 Mailing List, Patch, Vendor Advisory
• https://cloud.google.com/blog/products/identity-security/google-cloud-mitigated-largest-ddos-attack-peaking-above-398-million-rps/ Technical Description, Vendor Advisory
• https://cloud.google.com/blog/products/identity-security/how-it-works-the-novel-http2-rapid-reset-ddos-attack Technical Description, Vendor Advisory
• https://community.traefik.io/t/is-traefik-vulnerable-to-cve-2023-44487/20125 Vendor Advisory
• https://forums.swift.org/t/swift-nio-http2-security-update-cve-2023-44487-http-2-dos/67764 Vendor Advisory
• https://gist.github.com/adulau/7c2bfb8e9cdbe4b35a5e131c66a0c088 Issue Tracking, Patch
• https://github.com/advisories/GHSA-qppj-fm5r-hxr3 Vendor Advisory
• https://github.com/advisories/GHSA-vx74-f528-fxqg Mitigation, Patch, Vendor Advisory
• https://github.com/advisories/GHSA-xpw8-rcwv-8f8p Patch, Vendor Advisory
• https://github.com/apache/trafficserver/pull/10564 Issue Tracking, Patch
• https://github.com/arkrwn/PoC/tree/main/CVE-2023-44487 Vendor Advisory
• https://github.com/caddyserver/caddy/issues/5877 Issue Tracking, Vendor Advisory
• https://github.com/dotnet/announcements/issues/277 Issue Tracking, Mitigation, Vendor Advisory
• https://github.com/envoyproxy/envoy/pull/30055 Issue Tracking, Patch
• https://github.com/etcd-io/etcd/issues/16740 Issue Tracking, Patch
• https://github.com/facebook/proxygen/pull/466 Issue Tracking, Patch
• https://github.com/grpc/grpc-go/pull/6703 Issue Tracking, Patch
• https://github.com/h2o/h2o/pull/3291 Issue Tracking, Patch
• https://github.com/h2o/h2o/security/advisories/GHSA-2m7v-gc89-fjqf Vendor Advisory
• https://github.com/kazu-yamamoto/http2/commit/f61d41a502bd0f60eb24e1ce14edc7b6df6722a1 Patch
• https://github.com/kubernetes/kubernetes/pull/121120 Issue Tracking, Patch
• https://github.com/line/armeria/pull/5232 Issue Tracking, Patch
• https://github.com/linkerd/website/pull/1695/commits/4b9c6836471bc8270ab48aae6fd2181bc73fd632 Patch
• https://github.com/microsoft/CBL-Mariner/pull/6381 Issue Tracking, Patch
• https://github.com/netty/netty/commit/58f75f665aa81a8cbcf6ffa74820042a285c5e61 Patch
• https://github.com/nghttp2/nghttp2/pull/1961 Issue Tracking, Patch
• https://github.com/opensearch-project/data-prepper/issues/3474 Issue Tracking, Patch
• https://github.com/projectcontour/contour/pull/5826 Issue Tracking, Patch
• https://groups.google.com/g/golang-announce/c/iNNxDTCjZvo Mailing List, Release Notes, Vendor Advisory
• https://istio.io/latest/news/security/istio-security-2023-004/ Vendor Advisory
• https://linkerd.io/2023/10/12/linkerd-cve-2023-44487/ Vendor Advisory
• https://mailman.nginx.org/pipermail/nginx-devel/2023-October/S36Q5HBXR7CAIMPLLPRSSSYR4PCMWILK.html Mailing List, Patch, Third Party Advisory
• https://msrc.microsoft.com/blog/2023/10/microsoft-response-to-distributed-denial-of-service-ddos-attacks-against-http/2/ Patch, Vendor Advisory
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-44487 Mitigation, Patch, Vendor Advisory
• https://my.f5.com/manage/s/article/K000137106 Vendor Advisory
• https://netty.io/news/2023/10/10/4-1-100-Final.html Release Notes, Vendor Advisory
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-http2-reset-d8Kf32vZ Vendor Advisory
• https://security.paloaltonetworks.com/CVE-2023-44487 Vendor Advisory
• https://ubuntu.com/security/CVE-2023-44487 Vendor Advisory
• https://www.debian.org/security/2023/dsa-5521 Mailing List, Vendor Advisory
• https://www.debian.org/security/2023/dsa-5522 Mailing List, Vendor Advisory
• https://www.haproxy.com/blog/haproxy-is-not-affected-by-the-http-2-rapid-reset-attack-cve-2023-44487 Third Party Advisory, Vendor Advisory
• https://www.netlify.com/blog/netlify-successfully-mitigates-cve-2023-44487/ Vendor Advisory
• https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/ Mitigation, Vendor Advisory

Links in CISA's notes

• https://www.cisa.gov/news-events/alerts/2023/10/10/http2-rapid-reset-vulnerability-cve-2023-44487
• https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/
• https://nvd.nist.gov/vuln/detail/CVE-2023-44487

NVD details

CWE (NVD)

NVD-CWE-noinfo by nvd@nist.gov, CWE-400 by CISA ADP

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS versions in NVD

V31

Last modified in NVD

2026-08-11T19:37:30.880

Where each value comes from

This product uses data from the NVD API but is not endorsed or certified by the NVD. CISA does not endorse Sysprobs. Methodology.