CVE-2026-54425

/// Technical description

Uncontrolled recursion in the HTTP/2 HPACK decoder in Apache bRPC before 1.18.0 allows remote attackers to cause denial of service by sending a crafted HTTP/2 header block containing many consecutive Dynamic Table Size Update entries. Each update was decoded by recursively invoking the HPACK decoder, which could exhaust the thread stack before a header field or end of input was reached.

Root Cause:

The bRPC HPACK decoder recursively decoded the next entry after processing a Dynamic Table Size Update. The decoder did not bound the recursion depth, so a long sequence of update entries could consume excessive stack space.

Affected Scenarios:

Use bRPC with the built-in HTTP/2 implementation to accept HTTP/2 traffic from an untrusted network.

How to Fix:

1. Upgrade bRPC to version 1.18.0, which fixes this issue.

2. Apply this patch: https://github.com/apache/brpc/pull/3343

Note:

The fix changes HPACK Dynamic Table Size Update decoding to use iterative parsing instead of recursive pars

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References