Is CVE-2026-27017 actively exploited?

No active exploitation of CVE-2026-27017 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-27017 be exploited remotely?

Yes. CVE-2026-27017 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-27017?

CVE-2026-27017 has a CVSS score of 5.3 (MEDIUM) and an EPSS exploitation probability of 0.02%.

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MEDIUM

CVE-2026-27017

CWE-1240Published: February 20, 2026· Updated: Feb 20, 2026

5.3

CVSS v3.1

EPSS:0.02%probability of exploitation in 30 daysPercentile:5.1th

Official Description

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 cipher suite selection. When Chrome selects the preferred cipher suite in the outer ClientHello and for ECH, it does so consistently based on hardware support—for example, if it prefers AES for the outer cipher suite, it also uses AES for ECH. However, the Chrome parrot in uTLS hardcodes AES preference for outer cipher suites but selects the ECH cipher suite randomly between AES and ChaCha20. This creates a 50% chance of selecting ChaCha20 for ECH while using AES for the outer cipher suite, a combination impossible in Chrome. This issue only affects GREASE ECH; in real ECH, Chrome selects the first valid cipher suite when AES is preferred, which uTLS handles correctly. This issue has been fixed in version 1.8.1.

NVD Source

Technical Analysis

CVE-2026-27017 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.