Vulnerability-Lookup

FKIE_CVE-2026-78048

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

Severity

Summary

A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version < 1.18.0) on all platforms allows a remote attacker to crash the server process by sending a crafted sequence of HPACK headers, resulting in a denial of service. Root Cause: In src/brpc/details/hpack.cpp, IndexTable::Init sizes the dynamic-table ring buffer as num_headers = max_size / (32 + 2), i.e. it assumes a minimum table entry of 34 bytes (name >= 1 byte + value >= 1 byte + 32 bytes of overhead). However, RFC 7541 section 4.1 specifies that the minimum entry size is 33 bytes, because the value may be empty (name >= 1 byte + value == 0 + 32 bytes). For the default 4096-byte table this allocates only 120 slots (4096/34). Eviction in AddHeader is driven by byte usage (_max_size), not by slot count, so a peer can add 121 minimal 33-byte entries (121*33 = 3993 <= 4096) without triggering eviction. The 121st AddHeader then hits CHECK(!_header_queue.full()), which aborts the process. Affected Scenarios: Use a bRPC server that serves HTTP/2 or gRPC requests (e.g. via the h2 protocol) from an untrusted network. The malicious header block is processed during HPACK decoding of incoming requests without authentication. How to Fix: (Choose one of the following options) 1. Upgrade bRPC to version 1.18.0, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3462 Note: The fix sizes the dynamic table for the 33-byte minimum entry (max_size / (32 + 1)) and ensures at least one ring-buffer slot is kept when max_size is smaller than the minimum entry, so that initialization cannot fail on malloc(0).

References

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

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://github.com",
          "defaultStatus": "unaffected",
          "packageName": "apache/brpc",
          "packageURL": "pkg:github/apache/brpc",
          "product": "Apache bRPC",
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              "version": "0",
              "versionType": "semver"
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      "lang": "en",
      "value": "A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version \u003c 1.18.0) on all platforms allows a remote attacker to crash the server process by sending a crafted sequence of HPACK headers, resulting in a denial of service.\n\nRoot Cause:\nIn src/brpc/details/hpack.cpp, IndexTable::Init sizes the dynamic-table ring buffer as num_headers = max_size / (32 + 2), i.e. it assumes a minimum table entry of 34 bytes (name \u003e= 1 byte + value \u003e= 1 byte + 32 bytes of overhead). However, RFC 7541 section 4.1 specifies that the minimum entry size is 33 bytes, because the value may be empty (name \u003e= 1 byte + value == 0 + 32 bytes). For the default 4096-byte table this allocates only 120 slots (4096/34). Eviction in AddHeader is driven by byte usage (_max_size), not by slot count, so a peer can add 121 minimal 33-byte entries (121*33 = 3993 \u003c= 4096) without triggering eviction. The 121st AddHeader then hits CHECK(!_header_queue.full()), which aborts the process.\n\nAffected Scenarios:\nUse a bRPC server that serves HTTP/2 or gRPC requests (e.g. via the h2 protocol) from an untrusted network. The malicious header block is processed during HPACK decoding of incoming requests without authentication.\n\nHow to Fix: \n(Choose one of the following options)\u00a0\n1. Upgrade bRPC to version 1.18.0, which fixes this issue.\n2. Apply this patch:\u00a0https://github.com/apache/brpc/pull/3462\n\nNote:\nThe fix sizes the dynamic table for the 33-byte minimum entry (max_size / (32 + 1)) and ensures at least one ring-buffer slot is kept when max_size is smaller than the minimum entry, so that initialization cannot fail on malloc(0)."
    }
  ],
  "id": "CVE-2026-78048",
  "lastModified": "2026-10-21T12:17:23.213",
  "metrics": {},
  "published": "2026-10-21T12:17:23.213",
  "references": [
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      "source": "security@apache.org",
      "url": "https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb"
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  "sourceIdentifier": "security@apache.org",
  "vulnStatus": "Received",
  "weaknesses": [
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}

CVE-2026-78048 (GCVE-0-2026-78048)

Vulnerability from cvelistv5 – Published: 2026-10-21 11:51 – Updated: 2026-10-21 11:51

Title

Apache bRPC: Remote Denial of Service via Out-of-Bounds Dynamic Table Sizing in HPACK Decoder

Summary

Severity

No CVSS data available.

CWE

CWE-617 - Reachable Assertion

Assigner

apache CNA under the mitre root

CNA scorecard B 76/100 over 1087 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
Apache Software Foundation	Apache bRPC	Affected: 0 , < 1.18.0 (semver)

Credits

ubeddulla khan

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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