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"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"
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"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"
}
]
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"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"
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"packageName": "apache/brpc"
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"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",
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"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.
Root Cause:
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.
Affected Scenarios:
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.
How to Fix:
(Choose one of the following options)
1. Upgrade Apache bRPC to version 1.18.0, which fixes this issue.
2. Apply this patch: https://github.com/apache/brpc/pull/3325
Note:
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"
}
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"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"credits": [
{
"lang": "en",
"value": "Nikko Enggaliano Pratama",
"type": "finder"
}
],
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"engine": "Vulnogram 0.2.0"
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"adp": [
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"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",
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{
"Exploitation": "none"
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"Automatable": "no"
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"version": "2.0.3"
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"title": "CISA ADP Vulnrichment",
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"dateUpdated": "2026-10-21T13:07:53.942Z"
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