HIGH
CVE-2026-6409
CWE-20Published: April 16, 2026· Updated: Apr 17, 2026
7.1
CVSS v3.1
EPSS:0.07%probability of exploitation in 30 daysPercentile:22.0th
Official 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.
Technical Analysis
CVE-2026-6409 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation does not require any privileges, though user interaction (P) is needed, which slightly reduces the risk of mass automated attacks.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionP
ScopeX
Impact
Confidentiality
Integrity
Availability
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
Affected Vendors & Products
Mentioned vendors (from description):
PHP
CPE data not yet available in NVD for this CVE.
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
All References (1)
Quick Facts
CVE IDCVE-2026-6409
CVSS Score7.1 / 10
SeverityHIGH
WeaknessCWE-20
CISA KEVNo
EPSS (30d)0.07%
PublishedApr 16, 2026
Related CVEs (CWE-20)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-6409 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.