What is CVE-2026-27017?

CVE-2026-27017 is a medium-severity vulnerability in Refraction-networking Utls, classified under CWE-1240. CVSS score: 5.3/10. Published 2026-02-20.

How severe is CVE-2026-27017?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Refraction-networking Utls

CVE-2026-27017

uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. Versions 1.6.0 through 1.8.0 contain a fingerprint mismatch with Chrome when using GREASE ECH, related to…

EPSS: 0.002 (5.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Affected products

Refraction-networking Utls — versions >= 1.6.0, < 1.8.1

Weakness classification (CWE)

CWE-1240

References

security-advisories@github.com (x_refsource_CONFIRM, Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-27017?: CVE-2026-27017 is a medium-severity vulnerability in Refraction-networking Utls, classified under CWE-1240. CVSS score: 5.3/10. Published 2026-02-20.
How severe is CVE-2026-27017?: Medium severity. CVSS v3 base score is 5.3 out of 10.