[I've seen multiple news articles & blogs in the wake of the coordinated disclosure today, but no postings here yet, so lets start fixing that.]

Google, Cloudflare, AWS, and others released details today of a protocol-level issue in HTTP/2 being exploited in recent months for denial-of-service attacks:

https://cloud.google.com/blog/products/identity-security/how-it-works-the-novel-http2-rapid-reset-ddos-attack https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/ https://aws.amazon.com/blogs/security/how-aws-protects-customers-from-ddos-events/

This attack works via the multiplexed streams feature of HTTP/2, in which the client repeatedly makes a request for a new stream, and then immediately sends a RSTSTREAM frame to cancel them, resulting in the server doing lots of extra work to set up and tear down the streams, while not hitting any server-side limit on a maximum number of active streams per connection.

CVE-2023-44487 was issued to track this issue across implementations: https://www.cve.org/CVERecord?id=CVE-2023-44487

A script to check for affected implemenations has been posted at: https://github.com/bcdannyboy/CVE-2023-44487

Information I've found so far on open source implementations (most via the current listings in the CVE) include:

- Apache httpd: https://chaos.social/@icing/111210915918780532

- caddy: https://github.com/caddyserver/caddy/issues/5877

- envoy: https://github.com/envoyproxy/envoy/pull/30055

- golang: https://github.com/golang/go/issues/63417 https://groups.google.com/g/golang-announce/c/iNNxDTCjZvo

- h2o: https://github.com/h2o/h2o/security/advisories/GHSA-2m7v-gc89-fjqf https://github.com/h2o/h2o/pull/3291

- haproxy: https://github.com/haproxy/haproxy/issues/2312

- hyper: https://seanmonstar.com/post/730794151136935936/hyper-http2-rapid-reset-unaffected

- jetty: https://github.com/eclipse/jetty.project/issues/10679 https://github.com/eclipse/jetty.project/releases/tag/jetty-12.0.2 https://github.com/eclipse/jetty.project/releases/tag/jetty-11.0.17 https://github.com/eclipse/jetty.project/releases/tag/jetty-10.0.17 https://github.com/eclipse/jetty.project/releases/tag/jetty-9.4.53.v20231009

- netty: https://github.com/netty/netty/commit/58f75f665aa81a8cbcf6ffa74820042a285c5e61

- nghttp2: https://github.com/nghttp2/nghttp2/pull/1961 https://github.com/nghttp2/nghttp2/releases/tag/v1.57.0

- nginx: https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/ https://mailman.nginx.org/pipermail/nginx-devel/2023-October/S36Q5HBXR7CAIMPLLPRSSSYR4PCMWILK.html

- nodejs: https://github.com/nodejs/node/pull/50121

- proxygen: https://github.com/facebook/proxygen/pull/466

- swift-nio-http2: https://forums.swift.org/t/swift-nio-http2-security-update-cve-2023-44487-http-2-dos/67764

- tomcat: https://tomcat.apache.org/security-11.html#FixedinApacheTomcat11.0.0-M12 https://tomcat.apache.org/security-10.html#FixedinApacheTomcat10.1.14 https://tomcat.apache.org/security-9.html#FixedinApacheTomcat9.0.81 https://tomcat.apache.org/security-8.html#FixedinApacheTomcat8.5.94

-- -Alan Coopersmith- alan.coopersmith () oracle com Oracle Solaris Engineering - https://blogs.oracle.com/solaris

A vulnerability was found in a way nghttp2 processes incoming packets. Nghttpd, nghttp, and libnghttp2asio applications do not limit the memory usage for the incoming HTTP header field. If peer sends specially crafted HTTP/2 HEADERS frames and CONTINUATION frames, they will crash with out of memory error.

Upstream report and fix:

https://github.com/tatsuhiro-t/nghttp2/releases/tag/v1.7.1

The idle stream handling in nghttp2 before 1.6.0 allows attackers to have unspecified impact via unknown vectors, aka a heap-use-after-free bug.