ZDF
Sign inSign up

Vulnerabilities

Security research · CVE-2026-74755

Apache bRPC: Integer Underflow in mcpack2pb Parser Leading to Denial of Service

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

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-74755. EPSS is 0.57%. 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
0.57%
Remediation
Version ranges on file
Affected products
stated named in the record · vendor Apache Software Foundation Apache bRPC

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 without validating ; 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 , where 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

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-2026-74755

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-2026-74755. EPSS is 0.57%. 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-191: Integer Underflow. EPSS 0.57%. 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

    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 without validating ; when value_size is 0 the expression underflows to SIZE_MAX, resize() throws std::length_error, and because the ex

Sources

  • CVE.orgVulnerability recordCVE-2026-74755

    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 without valida

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-74755

    30-day exploitation probability 0.57%

    first.org
  • NIST NVDVulnerability recordCVE-2026-74755

    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 wi

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 6, 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