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Vendor Solution
The fix is expected in version 0.2.3. Upgrade to version 0.2.3 or later when available.
Vendor Workaround
Restrict the listener to known peer addresses or a private network, or use a TLS terminator that verifies client certificates against the intended CA. These controls reduce exposure but do not fix the proxy defect.
Tracking
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Wed, 23 Sep 2026 20:30:00 +0000
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ssvc
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Wed, 23 Sep 2026 19:15:00 +0000
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| 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. | |
| Title | s2s-proxy accepts untrusted client certificates | |
| Weaknesses | CWE-296 | |
| References |
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| Metrics |
cvssV4_0
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Subscriptions
No data.
Status: PUBLISHED
Assigner: Temporal
Published:
Updated: 2026-09-23T19:36:12.488Z
Reserved: 2026-09-23T16:06:36.077Z
Link: CVE-2026-96770
Updated: 2026-09-23T19:36:10.230Z
Status : Received
Published: 2026-09-23T19:19:55.013
Modified: 2026-09-23T20:17:27.193
Link: CVE-2026-96770
No data.
OpenCVE Enrichment
Updated: 2026-09-23T21:00:13Z
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CWE-296
Improper Following of a Certificate's Chain of Trust