CVE-2026-96770

CRITICALPre-NVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (15th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 9.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
57
EG Risk 57/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity93% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
15th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 23, 2026

Last Modified

September 24, 2026

Advisory Details (5)

Auto-updated Oct 3, 2026
Patch available. Sources: github_commit, github_pr.
github_pr Patch Available

Verify client certificate against configured CA in server TLS

Patch available: temporalio/s2s-proxy v0.2.3 (PR #296 merged 2026-09-23)

https://github.com/temporalio/s2s-proxy/pull/296
github_commit Patch Available

commit f1dc6b9a3919 (temporalio/s2s-proxy)

Patch available: temporalio/s2s-proxy v0.2.3 (contains commit f1dc6b9a3919)

https://github.com/temporalio/s2s-proxy/commit/f1dc6b9a3919d37e82545ab461cbe6bb62618d3c
github_commit Patch Available

commit d100c2258dbc (temporalio/s2s-proxy)

Patch available: temporalio/s2s-proxy v0.1.16 (contains commit d100c2258dbc)

https://github.com/temporalio/s2s-proxy/commit/d100c2258dbc37d7df51298ea045315f36c7eb3b
generic

s2s-proxy/encryption/tls.go at v0.2.2 · temporalio/s2s-proxy · GitHub

https://github.com/temporalio/s2s-proxy/blob/v0.2.2/encryption/tls.go#L47-L62
generic

Codecs and Encryption | Temporal Documentation

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

Vendor Advisories for CVE-2026-96770(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 55× in last 7d / 93× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-05 07:52 UTCGHSA enrichment
  2. 2026-10-05 03:45 UTCGHSA enrichment
  3. 2026-10-04 23:39 UTCEG score recompute
  4. 2026-10-04 23:38 UTCGHSA enrichment
  5. 2026-10-04 23:23 UTCEPSS rescore
  6. 2026-10-04 19:32 UTCGHSA enrichment
  7. 2026-10-04 15:25 UTCGHSA enrichment
  8. 2026-10-04 11:17 UTCGHSA enrichment
  9. 2026-10-04 07:09 UTCGHSA enrichment
  10. 2026-10-04 03:02 UTCGHSA enrichment
  11. 2026-10-03 22:56 UTCGHSA enrichment
  12. 2026-10-03 18:49 UTCGHSA enrichment
  13. 2026-10-03 14:43 UTCEG score recompute
  14. 2026-10-03 14:43 UTCGHSA enrichment
  15. 2026-10-03 14:26 UTCEPSS rescore
  16. 2026-10-03 10:35 UTCGHSA enrichment
  17. 2026-10-03 06:26 UTCGHSA enrichment
  18. 2026-10-03 02:18 UTCGHSA enrichment
  19. 2026-10-02 22:10 UTCGHSA enrichment
  20. 2026-10-02 18:03 UTCEG score recompute
  21. 2026-10-02 18:03 UTCGHSA enrichment
  22. 2026-10-02 17:57 UTCEPSS rescore
  23. 2026-10-02 13:56 UTCGHSA enrichment
  24. 2026-10-02 09:50 UTCGHSA enrichment
  25. 2026-10-02 05:43 UTCGHSA enrichment
Show 68 more
  1. 2026-10-02 01:36 UTCGHSA enrichment
  2. 2026-10-01 21:29 UTCEG score recompute
  3. 2026-10-01 21:29 UTCGHSA enrichment
  4. 2026-10-01 19:51 UTCEPSS rescore
  5. 2026-10-01 17:23 UTCGHSA enrichment
  6. 2026-10-01 13:16 UTCGHSA enrichment
  7. 2026-10-01 09:10 UTCGHSA enrichment
  8. 2026-10-01 05:03 UTCGHSA enrichment
  9. 2026-10-01 00:57 UTCGHSA enrichment
  10. 2026-09-30 20:50 UTCGHSA enrichment
  11. 2026-09-30 16:44 UTCEG score recompute
  12. 2026-09-30 16:44 UTCGHSA enrichment
  13. 2026-09-30 15:04 UTCEPSS rescore
  14. 2026-09-30 12:33 UTCGHSA enrichment
  15. 2026-09-30 08:25 UTCGHSA enrichment
  16. 2026-09-30 04:19 UTCGHSA enrichment
  17. 2026-09-30 00:12 UTCGHSA enrichment
  18. 2026-09-29 18:16 UTCEG score recompute
  19. 2026-09-29 18:16 UTCGHSA enrichment
  20. 2026-09-29 13:23 UTCGHSA enrichment
  21. 2026-09-29 09:13 UTCGHSA enrichment
  22. 2026-09-29 05:04 UTCGHSA enrichment
  23. 2026-09-29 00:57 UTCEG score recompute
  24. 2026-09-29 00:57 UTCGHSA enrichment
  25. 2026-09-28 20:51 UTCGHSA enrichment
  26. 2026-09-28 16:43 UTCEG score recompute
  27. 2026-09-28 16:43 UTCGHSA enrichment
  28. 2026-09-28 13:52 UTCEPSS rescore
  29. 2026-09-28 13:52 UTCEPSS rescore
  30. 2026-09-28 12:30 UTCGHSA enrichment
  31. 2026-09-28 08:22 UTCGHSA enrichment
  32. 2026-09-28 04:14 UTCGHSA enrichment
  33. 2026-09-28 00:08 UTCGHSA enrichment
  34. 2026-09-27 20:01 UTCGHSA enrichment
  35. 2026-09-27 15:53 UTCEG score recompute
  36. 2026-09-27 15:53 UTCGHSA enrichment
  37. 2026-09-27 13:49 UTCEPSS rescore
  38. 2026-09-27 11:47 UTCGHSA enrichment
  39. 2026-09-27 07:41 UTCGHSA enrichment
  40. 2026-09-27 03:34 UTCGHSA enrichment
  41. 2026-09-26 23:23 UTCGHSA enrichment
  42. 2026-09-26 19:13 UTCEG score recompute
  43. 2026-09-26 19:13 UTCGHSA enrichment
  44. 2026-09-26 15:59 UTCEPSS rescore
  45. 2026-09-26 15:06 UTCGHSA enrichment
  46. 2026-09-26 10:59 UTCGHSA enrichment
  47. 2026-09-26 06:48 UTCGHSA enrichment
  48. 2026-09-26 02:37 UTCEG score recompute
  49. 2026-09-26 02:37 UTCGHSA enrichment
  50. 2026-09-25 22:28 UTCGHSA enrichment
  51. 2026-09-25 18:18 UTCGHSA enrichment
  52. 2026-09-25 13:24 UTCGHSA enrichment
  53. 2026-09-25 09:15 UTCGHSA enrichment
  54. 2026-09-25 05:08 UTCGHSA enrichment
  55. 2026-09-25 01:02 UTCGHSA enrichment
  56. 2026-09-24 20:55 UTCGHSA enrichment
  57. 2026-09-24 16:57 UTCEG score recompute
  58. 2026-09-24 16:57 UTCGHSA enrichment
  59. 2026-09-24 14:04 UTCEPSS rescore
  60. 2026-09-24 12:51 UTCGHSA enrichment
  61. 2026-09-24 08:44 UTCGHSA enrichment
  62. 2026-09-24 04:37 UTCGHSA enrichment
  63. 2026-09-24 00:29 UTCGHSA enrichment
  64. 2026-09-23 20:22 UTCEG score recompute
  65. 2026-09-23 19:48 UTCEG score recompute
  66. 2026-09-23 19:26 UTCEG score recompute
  67. 2026-09-23 19:04 UTCEG score recompute
  68. 2026-09-23 19:04 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-96770?
CVE-2026-96770 is a critical vulnerability published on September 23, 2026. 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…
When was CVE-2026-96770 disclosed?
CVE-2026-96770 was first published on September 23, 2026, with the most recent update on September 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-96770 actively exploited?
CVE-2026-96770 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (15th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-96770?
CVE-2026-96770 has a CVSS base score of 9.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-96770?
A fix for CVE-2026-96770 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-96770 are linked in the Vendor Advisories panel on this page.

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