CVE-2026-26994: GO-2025-3638 - ServerHellos are accepted without checking TLS 1.3 downgrade canaries in github.com/refraction-networking/utls

CVE-2026-26994 · Severity: low · CVSS 3.1 · Published 2025-04-24

ServerHellos are accepted without checking TLS 1.3 downgrade canaries in github.com/refraction-networking/utls

Technologies: github.com/refraction-networking/utls (Go). Vendors: Go.

Quick answers

Is CVE-2026-26994 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-26994 being exploited in the wild.
How severe is CVE-2026-26994?
Low severity, with a CVSS score of 3.1, published 24 April 2025.
Which products and versions are affected?
github.com/refraction-networking/utls (Go) SEMVER:introduced=0,fixed=1.7.0, SEMVER:introduced=1.0.0,fixed=1.7.0.
Is there a fix for CVE-2026-26994?
Yes. github.com/refraction-networking/utls (Go): upgrade to 1.7.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-26994?
Check whether you run github.com/refraction-networking/utls (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/refraction-networking/utls (Go): upgrade to 1.7.0 or later
    go get github.com/refraction-networking/utls@v1.7.0

Affected products

  • github.com/refraction-networking/utls (Go) SEMVER:introduced=0,fixed=1.7.0, SEMVER:introduced=1.0.0,fixed=1.7.0

Identifiers

  • CVE-2026-26994
  • GHSA-pmc3-p9hx-jq96
  • GO-2025-3638

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