CVE-2026-96770

CRITICALPre-NVD 9.39.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (25th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-85567 (ENISA EUVD) · GHSA-fhc4-rg5x-86fx (GitHub Security Advisories)Source: ENISA EUVD

9.3EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • 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
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
57
EG Risk 57/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity93% × 45%
Impact severity (EG Severity): CVSS 9.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
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
25th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.3): severity, escalated by confirmed exploitation. This CVE's 9.3 is its impact severity (EG Severity), not escalated.

EG Severity
9.3 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track 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). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

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 pull request 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
Web page

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
Web page

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 15× in last 7d / 59× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 244 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 144 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 23:55 UTCEchelonGraph re-scored
  2. 2026-11-12 23:55 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  3. 2026-11-12 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  4. 2026-11-11 22:34 UTCEchelonGraph re-scored
  5. 2026-11-11 22:34 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  6. 2026-11-11 16:41 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  7. 2026-11-10 21:10 UTCEchelonGraph re-scored
  8. 2026-11-10 21:10 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  9. 2026-11-10 16:46 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  10. 2026-11-09 19:41 UTCEchelonGraph re-scored
  11. 2026-11-09 19:41 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  12. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  13. 2026-11-08 18:20 UTCEchelonGraph re-scored
  14. 2026-11-08 18:20 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  15. 2026-11-08 16:41 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  16. 2026-11-07 16:58 UTCEchelonGraph re-scored
  17. 2026-11-07 16:58 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  18. 2026-11-07 16:40 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  19. 2026-11-06 22:55 UTCOSV refresh
  20. 2026-11-06 16:40 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  21. 2026-11-06 15:37 UTCEchelonGraph re-scored
  22. 2026-11-06 15:37 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  23. 2026-11-05 16:39 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  24. 2026-11-05 14:15 UTCEchelonGraph re-scored
  25. 2026-11-05 14:15 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
Show 75 more
  1. 2026-11-04 16:37 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-11-04 12:54 UTCEchelonGraph re-scored
  3. 2026-11-04 12:54 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  4. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  5. 2026-11-03 11:32 UTCEchelonGraph re-scored
  6. 2026-11-03 11:32 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  7. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  8. 2026-11-02 10:09 UTCEchelonGraph re-scored
  9. 2026-11-02 10:09 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  10. 2026-11-01 16:36 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  11. 2026-11-01 08:45 UTCEchelonGraph re-scored
  12. 2026-11-01 08:45 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  13. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  14. 2026-10-31 07:24 UTCEchelonGraph re-scored
  15. 2026-10-31 07:24 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  16. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  17. 2026-10-30 06:03 UTCEchelonGraph re-scored
  18. 2026-10-30 06:02 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  19. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  20. 2026-10-29 04:40 UTCEchelonGraph re-scored
  21. 2026-10-29 04:40 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  22. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  23. 2026-10-28 03:13 UTCEchelonGraph re-scored
  24. 2026-10-28 03:12 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  25. 2026-10-27 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  26. 2026-10-27 01:41 UTCEchelonGraph re-scored
  27. 2026-10-27 01:41 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  28. 2026-10-26 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  29. 2026-10-25 20:23 UTCEchelonGraph re-scored
  30. 2026-10-25 20:23 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  31. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  32. 2026-10-25 13:48 UTCEchelonGraph re-scored
  33. 2026-10-24 19:01 UTCEchelonGraph re-scored
  34. 2026-10-24 19:01 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  35. 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  36. 2026-10-23 17:40 UTCEchelonGraph re-scored
  37. 2026-10-23 17:40 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  38. 2026-10-23 16:33 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  39. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  40. 2026-10-22 16:19 UTCEchelonGraph re-scored
  41. 2026-10-22 16:19 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  42. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.3% · 16th percentile
  43. 2026-10-21 14:35 UTCEchelonGraph re-scored
  44. 2026-10-21 14:35 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  45. 2026-10-20 16:34 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  46. 2026-10-20 13:11 UTCEchelonGraph re-scored
  47. 2026-10-20 13:11 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  48. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  49. 2026-10-19 11:47 UTCEchelonGraph re-scored
  50. 2026-10-19 11:47 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  51. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  52. 2026-10-18 09:46 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  53. 2026-10-18 02:57 UTCEchelonGraph re-scored
  54. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  55. 2026-10-17 08:22 UTCEchelonGraph re-scored
  56. 2026-10-17 08:22 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  57. 2026-10-16 16:45 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  58. 2026-10-16 07:01 UTCEchelonGraph re-scored
  59. 2026-10-16 07:00 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  60. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  61. 2026-10-15 05:37 UTCEchelonGraph re-scored
  62. 2026-10-15 05:37 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  63. 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  64. 2026-10-14 01:17 UTCEchelonGraph re-scored
  65. 2026-10-14 01:17 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  66. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  67. 2026-10-12 21:29 UTCEchelonGraph re-scored
  68. 2026-10-12 21:29 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  69. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  70. 2026-10-12 14:40 UTCEchelonGraph re-scored
  71. 2026-10-12 01:33 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  72. 2026-10-11 19:36 UTCGHSA enrichmentGHSA-fhc4-rg5x-86fx · GitHub severity CRITICAL
  73. 2026-10-11 19:11 UTCEchelonGraph re-scored
  74. 2026-10-11 16:27 UTCEchelonGraph re-scored
  75. 2026-10-11 15:29 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2026-96770?
CVE-2026-96770 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-96770 published?
The CVE record for CVE-2026-96770 was published on September 23, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 24, 2026; the record at its source may have been updated since.
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 (25th 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.

Dependency Blast Radius

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