CVE-2026-6409 PUBLISHED

Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input

Assigner: Google
Reserved: 15.04.2026 Published: 16.04.2026 Updated: 16.04.2026

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.

Metrics

CVSS 4.0

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
CVSS Score: 7.1

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	Passive

CVSS 4.0

Product Status

Vendor	Protocol Buffers
Product	Protobuf-php (Pecl)
Versions	Default: unaffected affected from 0 to 5.34.0-RC1 (excl.) affected from 0 to 4.33.6 (excl.)

Credits

https://github.com/34selen finder

References

https://github.com/protocolbuffers/protobuf/security/advisories/GHSA-p2gh-cfq4-4wjc

Problem Types

CWE-20 Improper input validation CWE

Impacts

CAPEC-130 Excessive Allocation