Vulnerability-Lookup

CVE-2026-96770 (GCVE-0-2026-96770)

Vulnerability from cvelistv5 – Published: 2026-09-23 18:58 – Updated: 2026-09-23 19:36

Title

s2s-proxy accepts untrusted client certificates

Summary

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

9.3 (Critical)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-23 19:36 UTC

CWE

CWE-296 - Improper Following of a Certificate's Chain of Trust

Assigner

Temporal CNA under the mitre root

CNA scorecard A 97/100 over 15 records in the last 180 days details

References

5 references

URL	Tags
https://github.com/temporalio/s2s-proxy/blob/v0.2…	product
https://github.com/temporalio/s2s-proxy/commit/d1…	product
https://github.com/temporalio/s2s-proxy/pull/296	patch
https://github.com/temporalio/s2s-proxy/commit/f1…	patch
https://docs.temporal.io/production-deployment/da…	product

Impacted products

1 product

Vendor	Product	Version	CPE status
Temporal Technologies, Inc.	s2s-proxy	Affected: 0.0.1-alpha , ≤ 0.2.2 (semver)	guessed

Credits

Praetorian, who reported this issue responsibly to Temporal Technologies

Show details on NVD website

JSON

To clipboard

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                  "type": "text/html",
                  "value": "\u003cp\u003eRestrict 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.\u003c/p\u003e"
                }
              ],
              "value": "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."
            }
          ]
        }
      },
      "cveMetadata": {
        "assignerOrgId": "61241ed8-fa44-4f23-92db-b8c443751968",
        "assignerShortName": "Temporal",
        "cveId": "CVE-2026-96770",
        "datePublished": "2026-09-23T18:58:46.233Z",
        "dateReserved": "2026-09-23T16:06:36.077Z",
        "dateUpdated": "2026-09-23T19:36:12.488Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-96770

Vulnerability from fkie_nvd - Published: 2026-09-23 19:19 - Updated: 2026-09-24 20:43

Severity

9.3 (Critical) - 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

Summary

References

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

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "github.com/temporalio/s2s-proxy",
          "product": "s2s-proxy",
          "programFiles": [
            "encryption/tls.go"
          ],
          "programRoutines": [
            {
              "name": "GetServerTLSConfig"
            }
          ],
          "repo": "https://github.com/temporalio/s2s-proxy",
          "vendor": "Temporal Technologies, Inc.",
          "versions": [
            {
              "lessThanOrEqual": "0.2.2",
              "status": "affected",
              "version": "0.0.1-alpha",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "security@temporal.io"
    }
  ],
  "cveTags": [],
  "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\u0027s RequireAnyClientCert mode when skipCAVerification is false. This mode checks that the client holds the certificate\u0027s 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\u0027s configuration and Temporal credentials. No certificate or private key trusted by the deployment, and no Temporal credential, is required."
    }
  ],
  "id": "CVE-2026-96770",
  "lastModified": "2026-09-24T20:43:32.537",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.3,
          "baseSeverity": "CRITICAL",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "HIGH",
          "subConfidentialityImpact": "HIGH",
          "subIntegrityImpact": "HIGH",
          "userInteraction": "NONE",
          "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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security@temporal.io",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-96770",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-23T19:36:07.279659Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-23T19:19:55.013",
  "references": [
    {
      "source": "security@temporal.io",
      "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"
    }
  ],
  "sourceIdentifier": "security@temporal.io",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-296"
        }
      ],
      "source": "security@temporal.io",
      "type": "Secondary"
    }
  ]
}

GHSA-FHC4-RG5X-86FX

Vulnerability from github – Published: 2026-09-23 21:30 – Updated: 2026-09-23 21:30

Details

Severity

9.3 (Critical)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-96770"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-296"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-23T19:19:55Z",
    "severity": "CRITICAL"
  },
  "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\u0027s RequireAnyClientCert mode when skipCAVerification is false. This mode checks that the client holds the certificate\u0027s 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\u0027s configuration and Temporal credentials. No certificate or private key trusted by the deployment, and no Temporal credential, is required.",
  "id": "GHSA-fhc4-rg5x-86fx",
  "modified": "2026-09-23T21:30:54Z",
  "published": "2026-09-23T21:30:54Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-96770 (GCVE-0-2026-96770)

FKIE_CVE-2026-96770

GHSA-FHC4-RG5X-86FX

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour