Input validation error in socket.io - #VU135352
Published: June 25, 2026
Vulnerability identifier: #VU135352
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: socket.io
Affected software:
socket.io
socket.io
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper input validation in WebTransport upgrade handling when processing a crafted WebTransport upgrade request with a chosen session ID. A remote attacker can send a specially crafted WebTransport upgrade request to cause a denial of service.
Only deployments with WebTransport support enabled are vulnerable. WebTransport is not enabled by default.
Remediation
Install security update from vendor's website.