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Vulnerabilities

Vulnerability · CVE-2026-78048

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

Published Oct 21, 2026 · catalog updated Oct 21, 2026 · Apache Software Foundation Apache bRPC

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-78048. EPSS is 0.63%. Act only if a listed version of Apache Software Foundation Apache bRPC is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.63%
Remediation
Version ranges on file
Affected products
stated named in the record · vendor Apache Software Foundation Apache bRPC

A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version = 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).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • stated named in the record< 1.18.0
  • vendor Apache Software Foundation Apache bRPCversion unspecified

How to fix CVE-2026-78048

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-78048. EPSS is 0.63%. Act only if a listed version of Apache Software Foundation Apache bRPC is installed.

Which versions are affected?

Compare what you have installed with named in the record < 1.18.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-617. EPSS 0.63%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 21, 2026 · NIST NVD

    Detected

    A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version = 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).

Sources

  • CVE.orgVulnerability recordCVE-2026-78048

    A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version = 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 e

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-78048

    30-day exploitation probability 0.63%

    first.org
  • NIST NVDVulnerability recordCVE-2026-78048

    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 servic

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 31, 2026
  • CVE.orgOct 21, 2026
  • NIST NVDOct 21, 2026