8.9

CVE-2026-61666: faye websocket-driver-ruby Uncaught Exception

CVSS: 8.9v4.0HighAwaiting analysis
AliasesUBUNTU-CVE-2026-61666DEBIAN-CVE-2026-61666CGA-289h-j34v-9pw6
Published 17-08-2026Last modified 17-08-2026
Open JSON

Vulnerability summary

CVE-2026-61666 is a high (CVSS 8.9) Uncaught Exception vulnerability in faye websocket-driver-ruby. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.5% of scored vulnerabilities.

Overall risk
36/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.9/10
010
High · v4.0 (CVE.org)
EPSS score
0.45%
0%100%
Low · +0.11 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-8JGJ-JJQH-5VQ2

Timeline

  1. 17-08-2026
    PublishedVulnerability first disclosed.
  2. 17-08-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

6 scores · 6 sources · 1 version

EPSS trend

Probability

0.45%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

+0.11 pp

From 0.34% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.45%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard29 products
  • commercial-gitlab-rails-ee-19.1All versions (No fix recorded) | < 19.1.9-r0
  • commercial-gitlab-rails-ee-19.2< 19.2.6-r0
  • commercial-gitlab-rails-ee-fips-19.1All versions (No fix recorded) | < 19.1.9-r0
  • commercial-gitlab-rails-ee-fips-19.2< 19.2.6-r0
  • gitlab-rails-ce-18.1< 18.1.6-r29
Debian1 product
  • ruby-websocket-driverAll versions (No fix recorded) | < 0.8.2-1
Faye1 product
RubyGems1 product
  • websocket-driver< 0.8.2
Ubuntu1 product
  • ruby-websocket-driverAll versions (No fix recorded)

5 vendors · 33 products

References

8 links