CVE-2026-6409

HIGH
MEDIUM Priority: 0.03 BB Relevance: 64/100
Published: 2026-04-16 Modified: 2026-10-26 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: Passive
S: X
AT: None
VC: None
VI: None
VA: High

Description

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.

Weakness Classification (1)

Bug Bounty Relevance

64 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity

CVSS Score

7.1 / 10.0 v4.0
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.36%
Raw Score 0.003600
Percentile 29.7%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00360
2026-10-28
0.00360

Intelligence Sources

nvd ref →