CVE-2026-96770

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.

CVSS

No CVSS.

References

Link	Resource
https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup
https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62
https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b
https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c
https://github.com/temporalio/s2s-proxy/pull/296

Configurations

No configuration.

History

23 Sep 2026, 19:19

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-09-23 19:19

Updated : 2026-09-24 20:43

NVD link : CVE-2026-96770

Mitre link : CVE-2026-96770

CVE.ORG link : CVE-2026-96770

JSON object : View

Products Affected

No product.

CWE

CWE-296

Improper Following of a Certificate's Chain of Trust

{"id": "CVE-2026-96770", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-96770", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-09-23T19:36:07.279659Z"}}], "cvssMetricV40": [{"type": "Secondary", "source": "security@temporal.io", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 9.3, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "valueDensity": "NOT_DEFINED", "vectorString": "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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "security@temporal.io", "affectedData": [{"repo": "https://github.com/temporalio/s2s-proxy", "vendor": "Temporal Technologies, Inc.", "product": "s2s-proxy", "versions": [{"status": "affected", "version": "0.0.1-alpha", "versionType": "semver", "lessThanOrEqual": "0.2.2"}], "packageName": "github.com/temporalio/s2s-proxy", "programFiles": ["encryption/tls.go"], "collectionURL": "https://pkg.go.dev", "defaultStatus": "unaffected", "programRoutines": [{"name": "GetServerTLSConfig"}]}]}], "published": "2026-09-23T19:19:55.013", "references": [{"url": "https://docs.temporal.io/production-deployment/data-encryption#codec-server-setup", "source": "security@temporal.io"}, {"url": "https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62", "source": "security@temporal.io"}, {"url": "https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b", "source": "security@temporal.io"}, {"url": "https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c", "source": "security@temporal.io"}, {"url": "https://github.com/temporalio/s2s-proxy/pull/296", "source": "security@temporal.io"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "security@temporal.io", "description": [{"lang": "en", "value": "CWE-296"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-09-24T20:43:32.537", "sourceIdentifier": "security@temporal.io"}