Apache bRPC: Null pointer dereference in MySQL reply parser leading to client crash

Summary

The MySQL client response parser in Apache bRPC dereferences a null pointer when the server peer sends a zero-payload-length response packet. A response packet whose declared payload length is zero is accepted by the frame-length check (is_full_package), after which the parser reads the response type byte via an unbounded 5-byte fetch that returns nullptr, and type = p[4] dereferences it, crashing the client process. Root Cause: In brpc::policy::MysqlReply::ConsumePartialIOBuf, buf.fetch(header, 5) returns nullptr when the buffered data only holds the 4-byte header of a zero-length packet, then the code reads p[4] (and, in the fast-auth path, p2[4]) without checking for a null or zero-length packet. Affected Scenarios: A brpc MySQL client connecting to a malicious or compromised MySQL server (or a MITM) can be crashed by a zero-length server response packet, resulting in denial of service of the client. Fix: The fix rejects zero-length response packets (returning PARSE_ERROR_ABSOLUTELY_WRONG) both for the initial response type determination and after a fast-auth marker, before reading the type byte. Upgrade to the Apache bRPC version 1.18.0 or apply the PR patch at https://github.com/apache/brpc/pull/3536.

Timeline

1. Oct 21, 2026, 12:19 PM UTCCVE published
2. Oct 22, 2026, 9:34 PM UTCFirst seen by cve.now
3. Oct 26, 2026, 1:39 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

4. Oct 26, 2026, 1:39 PM UTCRecord last updated

Affected versions

• apache/brpc

  through 1.11.0

References 2