# CVE-2026-96770: s2s-proxy TLS client certificate verification bypass

Source: https://junglewise.ai/threats/cve-2026-96770-all-published-s2s-proxy-versions-through-0-2-2-are-affected-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-96770 · Severity: info · Published 2026-09-23

s2s-proxy is a service-to-service proxy for Temporal workflow systems that secures connections between services. Versions up to 0.2.2 improperly validate TLS client certificates, allowing attackers to connect with self-signed certificates and invoke proxied RPC calls without legitimate credentials. An attacker can bypass authentication controls and access Temporal workflows and data without authorization.

Vendors: [Temporal](https://junglewise.ai/threats/vendors/temporal).

## Quick answers

**Is CVE-2026-96770 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-96770 being exploited in the wild.

**How severe is CVE-2026-96770?** Informational severity, published 23 September 2026.

**Which products and versions are affected?** Temporal S2s-Proxy 0.1.16 through 0.2.2.

**Is there a fix for CVE-2026-96770?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-96770 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-96770?** Check whether you run Temporal S2s-Proxy 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.

## Technical details

In s2s-proxy versions 0.1.16 through 0.2.2, TLS server listeners configured with skipCAVerification=false incorrectly use Go's RequireAnyClientCert mode, which verifies certificate possession but does not validate the certificate against the configured CA. An attacker can establish a TLS connection using any self-signed certificate, then invoke RPC methods allowed by the proxy's configuration and gain unauthorized access to Temporal credentials and workflows. The vulnerability is a certificate validation bypass requiring only network access to the proxy's TLS listener.

## Affected products

- Temporal s2s-proxy 0.1.16 through 0.2.2

## Timeline

- 2026-09-23: disclosed

## References

- [https://pkg.go.dev/](https://pkg.go.dev/)
- [https://docs.temporal.io/production-deployment/data-encryption](https://docs.temporal.io/production-deployment/data-encryption)