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TI-2026-78739 Aliases CVE-2026-78048GHSA-gjf5-p37j-frg4

Remote denial of service in Apache bRPC HPACK header decoder

Priority MEDIUM 40CWE-617Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-617.

Summary

Apache bRPC before 1.18.0 on all platforms has a reachable assertion in the HPACK header decoder of its HTTP/2 and gRPC stack (CWE-617). The dynamic table is sized for a 34-byte minimum entry, but RFC 7541 allows 33 bytes, so a peer can add more entries than there are slots. A remote attacker without authentication can crash the server process by sending a crafted sequence of HPACK headers.

Written with Claude Haiku 5.5 from the sources below · 2026-10-30

Description from the CNA

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).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0063 50th percentileScored 2026-11-07
Fix Fixed Apache bRPC (Apache Software Foundation): 1.18.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ApacheApache bRPCbefore 1.18.01.18.0Patch availableCNA
  • Apache bRPC VendorApache Affected before 1.18.0 Fixed in 1.18.0 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:apache:brpc:*:*:*:*:*:*:*:*——Apache
  • cpe:2.3:a:apache:brpc:*:*:*:*:*:*:*:* Versions — — ·Apache

Remediation

Upgrade Apache bRPC to version 1.18.0, which fixes this issue. Alternatively, apply the patch from pull request 3462 in the Apache bRPC repository.

Written with Claude Haiku 5.5 from the sources below · 2026-10-30

  • Fix · CNA Apache bRPC (Apache Software Foundation) Fixed in 1.18.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Apache bRPC — lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb

    35 records Highest priority Priority MEDIUM 18 MEDIUM, 17 LOW

    Other records, highest priority first

    • TI-2026-78552 Out-of-bounds write in Apache bRPC Redis command parserPriority MEDIUM 49
    • TI-2026-78757 Authentication bypass in Apache bRPC servers using internal_portPriority MEDIUM 48
    • TI-2026-78742 Missing authentication in Apache bRPC streaming RPC framesPriority MEDIUM 48
    Show all 35 records → Advisory →

Timeline

  1. 2026-10-21 Threatist record created from CVE-2026-78048
  2. 2026-10-21 Alias added: GHSA-gjf5-p37j-frg4
  3. 2026-10-30 CVSS score added · CISA ADP
  4. 2026-10-30 CISA SSVC decision points changed
  5. 2026-10-31 EPSS moved to the 50th–90th percentile
  6. 2026-11-01 Priority changed: LOW → MEDIUM

References

Advisory 1

  • TI-2025-18529 Apache Tomcat: Potential RCE and/or information disclosure and/or information corruption with partial PUT KEVCVSS 3.1CRITICAL 10.0
  • TI-2024-30292 Apache OFBiz: Confused controller-view authorization logic (forced browsing) KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-26062 Apache OFBiz: Unauthenticated endpoint could allow execution of screen rendering code KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-21190 Apache OFBiz: Path traversal leading to RCE KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-18186 Apache HugeGraph-Server: Command execution in gremlin KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-25106 Deserialization of untrusted data in Apache ActiveMQ KEVCVSS 3.1CRITICAL 10.0
See all 4053 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences