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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-27017

20
FAUCET Score

CVE-2026-27017 describes a fingerprint mismatch vulnerability in uTLS versions 1.6.0 through 1.8.0, specifically impacting its Chrome parrot when using GREASE ECH. The issue arises from uTLS inconsistently selecting cipher suites for ECH compared to the outer ClientHello, creating a combination not seen in legitimate Chrome traffic. Rated 5.3 MEDIUM, this network-exploitable vulnerability has low impact (C:L/I:N/A:N) and does not require user interaction or privileges. There is no known active exploitation, public exploit code, or Metasploit/Nuclei modules, though it has received some community and media attention.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.6.0, < 1.8.1CPE matchmatch criteria
cpe:2.3:a:refraction-networking:utls:*:*:*:*:*:go:*:*

CVSS Data

CVSS version used by this source: 4.0

2.3LOW

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/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

Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
LOW
VS Integrity
NONE
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.15%
Probability of exploitation in next 30 days
EPSS Percentile
5.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0015 is in the 1st percentile among its peer group of 23,725 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
gopatch availablevia ghsa
Product: github.com/refraction-networking/utlsFixed in: 1.8.1

Vendor Advisories (1)

goGHSA-7m29-f4hw-g2vxlow

uTLS has a fingerprint vulnerability from GREASE ECH mismatch for Chrome parrots

Feb 18, 2026

References

github.com / refraction-networking/utls/security/advisories/GHSA-7m29-f4hw-g2vx
PatchVendor Advisory