CVE-2026-96770: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-fhc4-rg5x-86fx
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CWE-296
Published
Advisory Summary

CVE-2026-96770 is a CRITICAL security vulnerability vulnerability (CWE-296: Improper Following of a Certificate's Chain of Trust) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not follow, or incorrectly follows, the chain of trust for a certificate back to a trusted root certificate.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-96770 at a Glance

CVE Identifier CVE-2026-96770
GHSA Identifier GHSA-fhc4-rg5x-86fx
Severity CRITICAL
CVSS v3.1 Base Score N/A
CWE Classification CWE-296: Improper Following of a Certificate's Chain of Trust
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-96770

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-96770, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-296: Improper Following of a Certificate's Chain of Trust, where the product does not follow, or incorrectly follows, the chain of trust for a certificate back to a trusted root certificate. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

All published s2s-proxy versions through 0.2.2 are affected. In versions 0.1.16 through 0.2.2, TLS server listeners use Go's RequireAnyClientCert mode when skipCAVerification is false. This mode checks that the client holds the certificate's private key but does not verify the certificate against the configured CA. An attacker can therefore use a self-signed certificate and key to establish a TLS and yamux connection, then invoke RPCs allowed by the proxy's configuration and Temporal credentials. No certificate or private key trusted by the deployment, and no Temporal credential, is required.

References

NVD — CVE-2026-96770 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-96770
Software Source Repository REPOSITORY
https://github.com/temporalio/s2s-proxy/pull/296
Security Fix Commit FIX COMMIT
https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b
Security Fix Commit FIX COMMIT
https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c
docs.temporal.io/production-deployme... WEB
https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup
Software Source Repository REPOSITORY
https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62

Frequently Asked Questions

What is CVE-2026-96770?
CVE-2026-96770 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-296: Improper Following of a Certificate's Chain of Trust.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-96770?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-96770?
CVE-2026-96770 is classified under CWE-296: Improper Following of a Certificate's Chain of Trust (The product does not follow, or incorrectly follows, the chain of trust for a certificate back to a trusted root certificate.).
How can I check Maven dependencies for CVE-2026-96770?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fhc4-rg5x-86fx",
  "modified" : "2026-09-23T21:30:54Z",
  "published" : "2026-09-23T21:30:54Z",
  "aliases" : [ "CVE-2026-96770" ],
  "details" : "All published s2s-proxy versions through 0.2.2 are affected. In versions 0.1.16 through 0.2.2, TLS server listeners use Go's RequireAnyClientCert mode when skipCAVerification is false. This mode checks that the client holds the certificate's private key but does not verify the certificate against the configured CA. An attacker can therefore use a self-signed certificate and key to establish a TLS and yamux connection, then invoke RPCs allowed by the proxy's configuration and Temporal credentials. No certificate or private key trusted by the deployment, and no Temporal credential, is required.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-96770"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/s2s-proxy/pull/296"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c"
  }, {
    "type" : "WEB",
    "url" : "https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-296" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-23T19:19:55Z"
  }
}