GitHub Advisoryadvisory · Packagist
GHSA-p2gh-cfq4-4wjc Protobuf: Denial of Service issue through malicious messages containing negative varints or deep recursion
HIGH
Official page ↗
- Aliases
- CVE-2026-6409
- Ecosystem
- Packagist
- Packages
- google/protobuf
- Severity
- High
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Weaknesses
- CWE-400
- Reviewed
- 2026-03-25
Affected packages
• Packagist google/protobuf: < 4.33.6 → fixed in 4.33.6
Description
Impact
A Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input. Maliciously structured messages—specifically those containing negative `varint`s or deep recursion—can be used to crash the application, impacting service availability.
Patches
Patches have been released to 5.34.0-RC1 and 4.33.6.
Related
Alias · CVE (1)
- CVE-2026-6409 A Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input. vulnerability
Weakness · CWE (1)
- CWE-400 Uncontrolled Resource Consumption weakness
References
- https://github.com/protocolbuffers/protobuf/security/advisories/GHSA-p2gh-cfq4-4wjc web
- https://nvd.nist.gov/vuln/detail/CVE-2026-6409 advisory
- https://github.com/protocolbuffers/protobuf/issues/24159 web
- https://github.com/protocolbuffers/protobuf/issues/25067 web
- https://github.com/protocolbuffers/protobuf/commit/60e93d2d104f2af9cd345b1c6f3891d91430244a web
- https://github.com/protocolbuffers/protobuf/commit/c8e9b27d95c6ab2d0668b5889e7dac2c477b7038 web
- https://github.com/protocolbuffers/protobuf package