Protobuf: Denial of Service issue through malicious messages containing negative varints or deep recursion
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 varints 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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | google/protobuf | < 4.33.6 | 4.33.6 |
References
- https://github.com/protocolbuffers/protobuf/security/advisories/GHSA-p2gh-cfq4-4wjc
- https://nvd.nist.gov/vuln/detail/CVE-2026-6409
- https://github.com/protocolbuffers/protobuf/issues/24159
- https://github.com/protocolbuffers/protobuf/issues/25067
- https://github.com/protocolbuffers/protobuf/commit/60e93d2d104f2af9cd345b1c6f3891d91430244a
- https://github.com/protocolbuffers/protobuf/commit/c8e9b27d95c6ab2d0668b5889e7dac2c477b7038
- https://github.com/protocolbuffers/protobuf
- 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- Weakness (CWE)
CWE-400- Platform
- Composer
- Package
google/protobuf- Disclosed
- 25.03.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-p2gh-cfq4-4wjc - CC BY 4.0
Vulnerability history: google/protobuf
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 09.2017 03.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 3
Disclosures per year
- 2017: 1
- 2018: 0
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 1
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 1
-
Protobuf: Denial of Service issue through malicious messages containing negative varints or deep recursion this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.