{"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. Malformed zero-length padded DATA frames are rejected with HTTP/2 FRAME_SIZE_ERROR.","lang":"en","supportingMedia":[{"type":"text/html","base64":false,"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.<br><br>Root Cause:<br>The 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.<br><br>Affected Scenarios:<br>Apache 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.<br><br>How to Fix:<br>(Choose one of the following options)<br>1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.<br>2. Apply this patch: <a target=\"_blank\" rel=\"nofollow\" href=\"https://github.com/apache/brpc/pull/3325\">https://github.com/apache/brpc/pull/3325</a><br><br>Note:<br>The 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."}]}],"references":[{"url":"https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb","tags":["vendor-advisory"]}],"metrics":[{"other":{"type":"Textual description of severity","content":{"text":"high"}},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"credits":[{"lang":"en","value":"Nikko Enggaliano Pratama","type":"finder"}],"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-10-21T13:07:50.344384Z","id":"CVE-2026-56386","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-21T13:07:53.942Z"}}]}}