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CVE-2026-96770— s2s-proxy accepts untrusted client certificates

Quick assessment

Affected

Temporal Technologies, Inc. s2s-proxy

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

所有发布至 0.2.2 版本的 s2s-proxy 均受此漏洞影响。在 0.1.16 至 0.2.2 版本中，当（跳过 CA 验证）为 false 时，TLS 服务器监听器会启用 Go 语言的模式。该模式仅验证客户端持有对应证书的私钥，但不会将客户端证书与已配置的证书颁发机构（CA）进行验证。因此，攻击者可以使用自签名证书和密钥建立 TLS 连接以及 yamux 连接，然后调用由代理配置和 Temporal 凭证所允许执行的远程过程调用（RPC）。在此攻击过程中，无需使用部署环境中信任的证书或私钥，也无需持有有

CVSS 9.3 · Critical EPSS 0.32% · P25 Updated Sep 28, 2026

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle

Affected Version Matrix 1

Vendor	Product	Version Range	Status
Temporal Technologies, Inc.	s2s-proxy	`0.0.1-alpha≤ 0.2.2`	affected

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Vulnerability Information

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Vulnerability Title

s2s-proxy accepts untrusted client certificates

Source: CVE Program / CVE List V5

Vulnerability Description

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.

Source: CVE Program / CVE List V5

CVSS Information

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

Source: CVE Program / CVE List V5

Vulnerability Type

证书信任链回溯不恰当

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
Temporal Technologies, Inc.	s2s-proxy	0.0.1-alpha ~ 0.2.2	-

II. Public POCs for CVE-2026-96770

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-96770

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Patches & Fixes for CVE-2026-96770 (3)

Other References for CVE-2026-96770 (1)

🔗 s2s-proxy/encryption/tls.go at v0.2.2 · temporalio/s2s-proxy · GitHub Read full article product

Other References for CVE-2026-96770 (1)

https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup product

https://www.cve.org/CVERecord?id=CVE-2026-96770

IV. Related Vulnerabilities

Same vendor: Temporal Technologies, Inc.

Same weakness: CWE-296