GHSA-pmc3-p9hx-jq96

Source

https://github.com/advisories/GHSA-pmc3-p9hx-jq96

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/04/GHSA-pmc3-p9hx-jq96/GHSA-pmc3-p9hx-jq96.json

JSON Data

https://api.test.osv.dev/v1/vulns/GHSA-pmc3-p9hx-jq96

Related

CGA-xgh3-355v-3pmw

Published

2025-04-23T14:43:44Z

Modified

2025-04-23T14:43:44Z

Severity

6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS Calculator

Summary

uTLS ServerHellos are accepted without checking TLS 1.3 downgrade canaries

Details

Description

Before version 1.7.0, utls did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a utls ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a utls client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because utls did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint utls connections.

Fix Commit or Pull Request

refraction-networking/utls#337, specifically refraction-networking/utls@f8892761e2a4d29054264651d3a86fda83bc83f9

References

https://github.com/refraction-networking/utls/issues/181

Database specific

{
    "nvd_published_at": null,
    "cwe_ids": [
        "CWE-693"
    ],
    "severity": "MODERATE",
    "github_reviewed": true,
    "github_reviewed_at": "2025-04-23T14:43:44Z"
}

References

Affected packages

Go / github.com/refraction-networking/utls

Package

Name: github.com/refraction-networking/utls; View open source insights on deps.dev
Purl: pkg:golang/github.com/refraction-networking/utls

Affected ranges

Type: SEMVER
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

1.7.0