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

Source: https://junglewise.ai/threats/cve-2026-26994-utls-serverhellos-are-accepted-without-checking-tls-1-3-downgrade  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-04-24  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-refraction-networking-utls). Vendors: [Go](https://junglewise.ai/threats/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

  ```sh
  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

## Related threats

- [uTLS has a fingerprint vulnerability from GREASE ECH mismatch for Chrome parrots](https://junglewise.ai/threats/cve-2026-27017-utls-has-a-fingerprint-vulnerability-from-grease-ech-mismatch-for)
- [uTLS has a fingerprint vulnerability from missing padding extension for Chrome 120](https://junglewise.ai/threats/cve-2026-26995-utls-has-a-fingerprint-vulnerability-from-missing-padding)