Protobuf: Denial of Service issue through malicious messages containing negative varints or deep recursion
The advisory, in context
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 packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
Earlier releases before 4.33.6
Fixed in 4.33.6
202 explicitly affected versions
v3.1.0-alpha-1, v3.10.0, v3.10.0RC1, v3.11.0, v3.11.0RC1, v3.11.0RC2, v3.11.1, v3.11.2, v3.11.3, v3.11.4, v3.12.0, v3.12.0RC1, v3.12.0RC2, v3.12.1, v3.12.2, v3.12.4, v3.13.0, v3.13.0.1, v3.13.0RC3, v3.14.0, v3.14.0RC1, v3.14.0RC2, v3.14.0RC3, v3.15.0, v3.15.0RC1, v3.15.0RC2, v3.15.1, v3.15.2, v3.15.3, v3.15.4, v3.15.5, v3.15.6, v3.15.7, v3.15.8, v3.16.0, v3.16.0RC1, v3.16.0RC2, v3.17.0, v3.17.0RC1, v3.17.0RC2, v3.17.1, v3.17.2, v3.17.3, v3.18.0, v3.18.0RC1, v3.18.0RC2, v3.18.1, v3.18.2, v3.18.3, v3.19.0, v3.19.0RC1, v3.19.0RC2, v3.19.1, v3.19.2, v3.19.3, v3.19.4, v3.19.5, v3.19.6, v3.2.0-alpha-1, v3.20.0RC1, v3.20.0RC2, v3.20.1, v3.20.1RC1, v3.20.2, v3.20.3, v3.21.0, v3.21.0RC1, v3.21.0RC2, v3.21.1, v3.21.10, v3.21.11, v3.21.12, v3.21.2, v3.21.3, v3.21.4, v3.21.5, v3.21.6, v3.21.7, v3.21.8, v3.21.9, v3.22.0, v3.22.0RC3, v3.22.1, v3.22.2, v3.22.3, v3.22.4, v3.22.5, v3.23.0, v3.23.0RC1, v3.23.0RC2, v3.23.0RC3, v3.23.1, v3.23.2, v3.23.3, v3.23.4, v3.24.0, v3.24.0RC1, v3.24.0RC2, v3.24.0RC3, v3.24.1, v3.24.2, v3.24.3, v3.24.4, v3.25.0, v3.25.0RC1, v3.25.0RC2, v3.25.1, v3.25.2, v3.25.3, v3.25.4, v3.25.5, v3.25.6, v3.25.7, v3.25.8, v3.25.9, v3.3.0, v3.3.0rc1, v3.3.1, v3.3.2, v3.4.0, v3.4.0rc1, v3.4.0rc2, v3.4.0rc3, v3.4.1, v3.5.0, v3.5.0.1, v3.5.1, v3.5.1.1, v3.5.2, v3.6.0, v3.6.0.1, v3.6.0rc1, v3.6.0rc2, v3.6.1, v3.6.1.1, v3.6.1.2, v3.6.1.3, v3.7.0, v3.7.0-rc.3, v3.7.0rc1, v3.7.0rc2, v3.7.1, v3.8.0, v3.8.0RC1, v3.9.0, v3.9.0RC1, v3.9.1, v3.9.2, v4.0.0RC1, v4.0.0RC2, v4.26.0, v4.26.0RC1, v4.26.0RC2, v4.26.0RC3, v4.26.1, v4.27.0, v4.27.0RC1, v4.27.0RC2, v4.27.0RC3, v4.27.1, v4.27.2, v4.27.3, v4.27.4, v4.27.5, v4.28.0, v4.28.0RC1, v4.28.0RC2, v4.28.0RC3, v4.28.1, v4.28.2, v4.28.3, v4.29.0, v4.29.0RC1, v4.29.0RC2, v4.29.0RC3, v4.29.1, v4.29.2, v4.29.3, v4.29.4, v4.29.5, v4.29.6, v4.30.0, v4.30.0RC1, v4.30.0RC2, v4.30.1, v4.30.2, v4.31.0, v4.31.0RC1, v4.31.0RC2, v4.31.1, v4.32.0, v4.32.0RC1, v4.32.0RC2, v4.32.1, v4.33.0, v4.33.0RC1, v4.33.0RC2, v4.33.1, v4.33.2, v4.33.3, v4.33.4, v4.33.5
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.33.6"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v3.1.0-alpha-1",
"v3.10.0",
"v3.10.0RC1",
"v3.11.0",
"v3.11.0RC1",
"v3.11.0RC2",
"v3.11.1",
"v3.11.2",
"v3.11.3",
"v3.11.4",
"v3.12.0",
"v3.12.0RC1",
"v3.12.0RC2",
"v3.12.1",
"v3.12.2",
"v3.12.4",
"v3.13.0",
"v3.13.0.1",
"v3.13.0RC3",
"v3.14.0",
"v3.14.0RC1",
"v3.14.0RC2",
"v3.14.0RC3",
"v3.15.0",
"v3.15.0RC1",
"v3.15.0RC2",
"v3.15.1",
"v3.15.2",
"v3.15.3",
"v3.15.4",
"v3.15.5",
"v3.15.6",
"v3.15.7",
"v3.15.8",
"v3.16.0",
"v3.16.0RC1",
"v3.16.0RC2",
"v3.17.0",
"v3.17.0RC1",
"v3.17.0RC2",
"v3.17.1",
"v3.17.2",
"v3.17.3",
"v3.18.0",
"v3.18.0RC1",
"v3.18.0RC2",
"v3.18.1",
"v3.18.2",
"v3.18.3",
"v3.19.0",
"v3.19.0RC1",
"v3.19.0RC2",
"v3.19.1",
"v3.19.2",
"v3.19.3",
"v3.19.4",
"v3.19.5",
"v3.19.6",
"v3.2.0-alpha-1",
"v3.20.0RC1",
"v3.20.0RC2",
"v3.20.1",
"v3.20.1RC1",
"v3.20.2",
"v3.20.3",
"v3.21.0",
"v3.21.0RC1",
"v3.21.0RC2",
"v3.21.1",
"v3.21.10",
"v3.21.11",
"v3.21.12",
"v3.21.2",
"v3.21.3",
"v3.21.4",
"v3.21.5",
"v3.21.6",
"v3.21.7",
"v3.21.8",
"v3.21.9",
"v3.22.0",
"v3.22.0RC3",
"v3.22.1",
"v3.22.2",
"v3.22.3",
"v3.22.4",
"v3.22.5",
"v3.23.0",
"v3.23.0RC1",
"v3.23.0RC2",
"v3.23.0RC3",
"v3.23.1",
"v3.23.2",
"v3.23.3",
"v3.23.4",
"v3.24.0",
"v3.24.0RC1",
"v3.24.0RC2",
"v3.24.0RC3",
"v3.24.1",
"v3.24.2",
"v3.24.3",
"v3.24.4",
"v3.25.0",
"v3.25.0RC1",
"v3.25.0RC2",
"v3.25.1",
"v3.25.2",
"v3.25.3",
"v3.25.4",
"v3.25.5",
"v3.25.6",
"v3.25.7",
"v3.25.8",
"v3.25.9",
"v3.3.0",
"v3.3.0rc1",
"v3.3.1",
"v3.3.2",
"v3.4.0",
"v3.4.0rc1",
"v3.4.0rc2",
"v3.4.0rc3",
"v3.4.1",
"v3.5.0",
"v3.5.0.1",
"v3.5.1",
"v3.5.1.1",
"v3.5.2",
"v3.6.0",
"v3.6.0.1",
"v3.6.0rc1",
"v3.6.0rc2",
"v3.6.1",
"v3.6.1.1",
"v3.6.1.2",
"v3.6.1.3",
"v3.7.0",
"v3.7.0-rc.3",
"v3.7.0rc1",
"v3.7.0rc2",
"v3.7.1",
"v3.8.0",
"v3.8.0RC1",
"v3.9.0",
"v3.9.0RC1",
"v3.9.1",
"v3.9.2",
"v4.0.0RC1",
"v4.0.0RC2",
"v4.26.0",
"v4.26.0RC1",
"v4.26.0RC2",
"v4.26.0RC3",
"v4.26.1",
"v4.27.0",
"v4.27.0RC1",
"v4.27.0RC2",
"v4.27.0RC3",
"v4.27.1",
"v4.27.2",
"v4.27.3",
"v4.27.4",
"v4.27.5",
"v4.28.0",
"v4.28.0RC1",
"v4.28.0RC2",
"v4.28.0RC3",
"v4.28.1",
"v4.28.2",
"v4.28.3",
"v4.29.0",
"v4.29.0RC1",
"v4.29.0RC2",
"v4.29.0RC3",
"v4.29.1",
"v4.29.2",
"v4.29.3",
"v4.29.4",
"v4.29.5",
"v4.29.6",
"v4.30.0",
"v4.30.0RC1",
"v4.30.0RC2",
"v4.30.1",
"v4.30.2",
"v4.31.0",
"v4.31.0RC1",
"v4.31.0RC2",
"v4.31.1",
"v4.32.0",
"v4.32.0RC1",
"v4.32.0RC2",
"v4.32.1",
"v4.33.0",
"v4.33.0RC1",
"v4.33.0RC2",
"v4.33.1",
"v4.33.2",
"v4.33.3",
"v4.33.4",
"v4.33.5"
]
}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