Cloud Vulnerability DB
An open project to list all known cloud vulnerabilities and Cloud Service Provider security issues
Vulnerability DatabaseGHSA-pmc3-p9hx-jq96
GHSA-pmc3-p9hx-jq96:
vulnerability analysis and mitigation
Overview
GHSA-pmc3-p9hx-jq96 is a moderate severity vulnerability affecting the uTLS library (github.com/refraction-networking/utls) versions prior to 1.7.0. The vulnerability was discovered and disclosed on April 23, 2025, impacting the TLS 1.3 downgrade protection mechanism (GitHub Advisory).
Technical details
The vulnerability stems from uTLS's failure to implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. The vulnerability has a CVSS v3.1 score of 6.5 (Moderate) with a vector string of CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N, indicating network vector attack with low complexity and no required privileges or user interaction (GitHub Advisory).
Impact
An active network adversary could exploit this vulnerability 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. The server would respond with a TLS 1.2 ServerHello containing a downgrade canary in the ServerHello random field, which the client would accept without detection. Additionally, this vulnerability could be used by attackers to fingerprint uTLS connections (GitHub Advisory).
Mitigation and workarounds
The vulnerability has been patched in version 1.7.0 of the uTLS library. Users should upgrade to this version or later to receive the fix. The patch was implemented through pull request #337 with commit f889276 (GitHub PR).
Additional resources
Source: This report was generated using AI
Free Vulnerability Assessment
Benchmark your Cloud Security Posture
Evaluate your cloud security practices across 9 security domains to benchmark your risk level and identify gaps in your defenses.
Get a personalized demo
Ready to see Wiz in action?
“Best User Experience I have ever seen, provides full visibility to cloud workloads.”
David EstlickCISO
“Wiz provides a single pane of glass to see what is going on in our cloud environments.”
Adam FletcherChief Security Officer
“We know that if Wiz identifies something as critical, it actually is.”
Greg PoniatowskiHead of Threat and Vulnerability Management