Skip to content
Fencer Vulns
high 8.9

CVE-2026-61666 json

websocket-driver: Denial of service via malformed Host header

published 2026-07-21 3 mo ago modified 2026-11-02 6 d ago also GHSA-2x63-gw47-w4mm , EUVD-2026-60264

cvss
8.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.8.2, WebSocket::Driver.server() passes a malformed Host header to URI.parse in lib/websocket/http/request.rb without catching URI::InvalidURIError, allowing a remote client to crash a TCP-backed WebSocket server when the application does not catch the error from parse(). This issue is fixed in version 0.8.2.

Patch / fix

  • rubygems websocket-driver 0.8.2
  • ruby-websocket-driver Debian 14 0.8.2-1

debian advisories DEBIAN-CVE-2026-61666

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-61666 updated cvss 7.5

websocket-driver: github.com/faye/websocket-driver-ruby: websocket-driver: Denial of Service via malformed Host header

  • Red Hat Satellite 6 rubygem-websocket-driver
    under investigation
  • Red Hat 3scale API Management Platform 2 3scale-amp2/zync-rhel9, 3scale-amp2/system-rhel8, 3scale-amp2/system-rhel9
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
CNA 4.0 8.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/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 packages

ecosystem package affected fixed in
rubygems websocket-driver
<0.8.2
0.8.2

Affected products

  • faye websocket-driver-ruby

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.