CVE-2026-74755 (GCVE-0-2026-74755)

Vulnerability from cvelistv5 – Published: 2026-10-21 11:45 – Updated: 2026-10-21 11:45
VLAI
Title
Apache bRPC: Integer Underflow in mcpack2pb Parser Leading to Denial of Service
Summary
An integer underflow in the mcpack2pb component of Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to crash a bRPC server by sending a request containing a string field with a zero value_size. The UnparsedValue::as_string() function computes `_size - 1` without validating `_size`; when value_size is 0 the expression underflows to SIZE_MAX, resize() throws std::length_error, and because the exception is not caught on the request parsing path the process aborts (SIGABRT). Root Cause: In src/mcpack2pb/parser.cpp, UnparsedValue::as_string() resizes the output string to `_size - 1`, where `_size` is the value_size of a string field taken directly from the network data. A value_size of 0 underflows the unsigned size_t, and the subsequent resize() throws an exception that is not caught. Affected Scenarios: bRPC servers that accept nshead frames wired to the ubrpc mcpack2 adaptor (for example the NsheadService + UbrpcMcpack2Adaptor deployment pattern) can be crashed by a single unauthenticated request. Stock open-source bRPC registers the ubrpc/nshead_mcpack protocols as client-only, so default server configurations are not affected. How to Fix: 1. Upgrade bRPC to a version that includes this fix. 2. Apply the patch in PR  https://github.com/apache/brpc/pull/3450
Severity
No CVSS data available.
CWE
  • CWE-191 - Integer Underflow (Wrap or Wraparound)
Assigner
apache CNA under the mitre root
CNA scorecard B 76/100 over 1088 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Apache Software Foundation Apache bRPC Affected: 0 , < 1.18.0 (semver)
guessed Create a notification for this product.
Credits
Feng Zhijie (Independent security researcher)
Show details on NVD website
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