Vulnerability-Lookup

CVE-2026-56386 (GCVE-0-2026-56386)

Vulnerability from cvelistv5 – Published: 2026-10-21 11:37 – Updated: 2026-10-21 13:07

Title

Apache bRPC: Integer Underflow and Out-of-Bounds Read in HTTP/2 DATA Frame Parser

Summary

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.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-21 13:07 UTC

CWE

CWE-191 - Integer Underflow
CWE-125 - Out-of-bounds Read

Assigner

apache CNA under the mitre root

CNA scorecard B 76/100 over 1088 records in the last 180 days details

References

1 reference

URL	Tags
https://lists.apache.org/thread/2pf15ojj0vr7rtx95…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
Apache Software Foundation	Apache bRPC	Affected: 0 , < 1.18.0 (semver)	guessed

Credits

Nikko Enggaliano Pratama

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-56386

Vulnerability from fkie_nvd - Published: 2026-10-21 12:17 - Updated: 2026-10-22 16:56

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	security@apache.org	https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "lang": "en",
          "value": "CWE-125"
        },
        {
          "lang": "en",
          "value": "CWE-191"
        }
      ],
      "source": "security@apache.org",
      "type": "Secondary"
    }
  ]
}

GHSA-WJ5X-6JJ2-M348

Vulnerability from github – Published: 2026-10-21 12:31 – Updated: 2026-10-21 15:42

Details

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.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-56386"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-21T12:17:21Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-wj5x-6jj2-m348",
  "modified": "2026-10-21T15:42:26Z",
  "published": "2026-10-21T12:31:08Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56386"
    },
    {
      "type": "WEB",
      "url": "https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

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CVE-2026-56386 (GCVE-0-2026-56386)

FKIE_CVE-2026-56386

GHSA-WJ5X-6JJ2-M348

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