CVE-2026-6409

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

Published: Apr 16, 2026Updated: Apr 17, 2026 Sources: CVE List NVD BDUCWE-20

7.5HIGH

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAccess Vector

Network

AC:LAccess Complexity

Low

Impact

C:NConfidentiality

None

I:NIntegrity

None

A:HAvailability

Open in CVSS calculator →

Weaknesses

CWE-20

Affected Products

ООО «Ред Софт»

commercial·RUaka red soft

РЕД ОСOn-premOS

Operating Systems / linux-distro

Google Inc

commercial·USaka google

ProtobufLibraryLibrary

OSS Libraries / generic-library

Protocol Buffers

oss-projectaka protocol-buffer, protocolbuffers, google protocol buffers

Protobuf-php (Pecl)Library

OSS Libraries / generic-library

Exploitability

Official Patch Available

Is your org exposed to CVE-2026-6409?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

1 technique

Initial Access

View detailed technique mapping

References

https://github.com/protocolbuffers/protobuf/issues/25067

github.com

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

github.com

https://redos.red-soft.ru/support/secure/uyazvimosti-red-os-8-0/uyazvimost-protobuf-cve-2026-6409-8.0/?sphrase_id=1528323

redos.red-soft.ru

and 1 more references View all →

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-6409 and every CVE in our database. Create a free account — no credit card required.

Create Free Account

Plain-language analysis

Impact assessment and exploitation scenario in plain English

Attack graph visualization

Interactive attack path and kill chain mapping

Exploit details & PoC links

ExploitDB, Metasploit, GitHub PoCs with direct links

Nuclei scanner templates

Ready-to-use vulnerability scanner templates

Full remediation guide

Patch instructions, workarounds, and compliance impact

Interactive AI chat

Ask questions about this vulnerability in natural language

Related vulnerabilities

Semantically similar CVEs and attack patterns

REST API & MCP access

Integrate vulnerability data into your workflows