{"id":"CVE-2026-56386","revision":"d2c20fad838f4c6896057c20950da873","records":[{"revision":"d2c20fad838f4c6896057c20950da873","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-56386","aliases":[],"title":"Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser","description":"Integer underflow and out-of-bounds read in the HTTP/2 server DATA frame parser in Apache bRPC allows an unauthenticated remote attacker to cause denial of service by sending a malformed DATA frame with the PADDED flag set and a zero-length payload.\n\nRoot Cause:\nThe HTTP/2 DATA frame handler computed the fragment size from the attacker-controlled payload length and, when the PADDED flag was present, decremented the fragment size before ensuring that the frame contained the mandatory pad length byte. A zero-length padded DATA frame could therefore underflow the unsigned fragment size and read the pad length byte past the end of the frame buffer.\n\nAffected Scenarios:\nApache bRPC servers that accept HTTP/2 traffic are affected when a remote client can send crafted HTTP/2 frames to the server. HTTP/2 may be reached through cleartext h2c detection on an HTTP port or through TLS ALPN negotiation.\n\nHow to Fix:\n(Choose one of the following options)\n1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:  https://github.com/apache/brpc/pull/3325 \n\nNote:\nThe fix validates that a padded DATA frame has enough payload bytes for the pad length field before decrementing the fragment size or reading the pad length byte. Malformed zero-length padded DATA frames are rejected with HTTP/2 FRAME_SIZE_ERROR.","state":0,"publishedAt":"2026-10-21T11:37:47.458+00:00","modifiedAt":"2026-10-21T13:07:53.942+00:00","affected":[{"ecosystem":"https://github.com","name":"apache/brpc","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"Apache Software Foundation\",\n                    \"product\": \"Apache bRPC\",\n                    \"packageURL\": \"pkg:github/apache/brpc\",\n                    \"versions\": [\n                        {\n                            \"status\": \"affected\",\n                            \"version\": \"0\",\n                            \"lessThan\": \"1.18.0\",\n                            \"versionType\": \"semver\"\n                        }\n                    ],\n                    \"defaultStatus\": \"unaffected\",\n                    \"collectionURL\": \"https://github.com\",\n                    \"packageName\": \"apache/brpc\"\n                }"}],"metrics":[],"references":["https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-56386","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-56386","identifiers":["CVE-2026-56386"]},"retained":false,"historicalAffected":[]}],"coverage":[]}