{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-56386", "assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "state": "PUBLISHED", "assignerShortName": "apache", "dateReserved": "2026-06-21T04:43:24.873Z", "datePublished": "2026-10-21T11:37:47.458Z", "dateUpdated": "2026-10-21T13:07:53.942Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09", "shortName": "apache", "dateUpdated": "2026-10-21T11:37:47.458Z"}, "title": "Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser", "problemTypes": [{"descriptions": [{"description": "CWE-191 Integer Underflow", "lang": "en", "cweId": "CWE-191", "type": "CWE"}, {"description": "CWE-125 Out-of-bounds Read", "lang": "en", "cweId": "CWE-125", "type": "CWE"}]}], "source": {"discovery": "EXTERNAL"}, "affected": [{"vendor": "Apache Software Foundation", "product": "Apache bRPC", "packageURL": "pkg:github/apache/brpc", "versions": [{"status": "affected", "version": "0", "lessThan": "1.18.0", "versionType": "semver"}], "defaultStatus": "unaffected", "collectionURL": "https://github.com", "packageName": "apache/brpc"}], "descriptions": [{"value": "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. 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