CVE-2026-11718

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 92% of all CVEs by exploit prediction. 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, nvd
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox.

When the toolbox validates an opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), it decodes the response into an introspectResp struct. However, the subsequent claim-checking logic (validateClaims) evaluates the issuer condition as if a.issuer != "" && iss != "". If the external OAuth provider's introspection response omits the optional iss (issuer) field completely, the variable iss defaults to an empty string. This causes the conditional block to evaluate to false and be skipped silently. Consequently, the application accepts tokens issued by unauthorized or unintended third-party identity providers.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
46(Track)
EG Risk 46/100SSVC: Track

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
Severity91% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
8%
KEV
Not listed

Published

June 18, 2026

Last Modified

August 17, 2026

Advisory Details (1)

Auto-updated Aug 1, 2026
Patch available. Sources: github_pr.
github_pr Patch Available

fix(auth/generic): enforce issuer presence in opaque token validation

Patch available: googleapis/mcp-toolbox v1.4.0 (PR #3360 merged 2026-06-04)

https://github.com/googleapis/mcp-toolbox/pull/3360

Vendor Advisories for CVE-2026-11718(1)

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

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/googleapis/mcp-toolbox—1.4.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 55× 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. 2026-08-23 01:12 UTCEG score recompute
  2. 2026-08-23 00:19 UTCEPSS rescore
  3. 2026-08-21 23:48 UTCEPSS rescore
  4. 2026-08-21 01:14 UTCEG score recompute
  5. 2026-08-20 22:55 UTCEPSS rescore
  6. 2026-08-20 08:09 UTCEG score recompute
  7. 2026-08-19 17:03 UTCEPSS rescore
  8. 2026-08-19 07:44 UTCEG score recompute
  9. 2026-08-18 13:48 UTCEPSS rescore
  10. 2026-08-17 16:28 UTCEG score recompute▼ 0.20
  11. 2026-08-17 16:09 UTCNVD updateCVSS v3 → 9.1
  12. 2026-08-16 20:44 UTCEG score recompute
  13. 2026-08-16 14:56 UTCEPSS rescore
  14. 2026-08-16 05:46 UTCEG score recompute
  15. 2026-08-16 02:14 UTCEPSS rescore
  16. 2026-08-15 04:09 UTCEG score recompute
  17. 2026-08-15 01:30 UTCEPSS rescore
  18. 2026-08-13 23:12 UTCEG score recompute
  19. 2026-08-13 22:00 UTCEPSS rescore
  20. 2026-08-12 16:31 UTCEG score recompute
  21. 2026-08-12 13:50 UTCEPSS rescore
  22. 2026-08-11 15:26 UTCEG score recompute
  23. 2026-08-11 13:42 UTCEPSS rescore
  24. 2026-08-11 03:02 UTCEG score recompute
  25. 2026-08-10 23:59 UTCEPSS rescore
Show 75 more
  1. 2026-08-09 17:35 UTCEG score recompute
  2. 2026-08-09 13:46 UTCEPSS rescore
  3. 2026-08-08 16:47 UTCEG score recompute
  4. 2026-08-08 16:37 UTCEPSS rescore
  5. 2026-08-07 20:07 UTCEG score recompute
  6. 2026-08-06 14:54 UTCEG score recompute
  7. 2026-08-06 13:46 UTCEPSS rescore
  8. 2026-08-05 22:14 UTCEG score recompute
  9. 2026-08-05 19:17 UTCEPSS rescore
  10. 2026-08-04 15:23 UTCEG score recompute
  11. 2026-08-04 15:09 UTCEPSS rescore
  12. 2026-08-04 10:38 UTCEPSS rescore
  13. 2026-08-03 14:23 UTCEG score recompute
  14. 2026-08-03 10:35 UTCEPSS rescore
  15. 2026-08-02 06:00 UTCEG score recompute
  16. 2026-08-02 02:26 UTCEPSS rescore
  17. 2026-08-01 05:10 UTCEG score recompute
  18. 2026-08-01 04:15 UTCEPSS rescore
  19. 2026-07-30 22:28 UTCEG score recompute
  20. 2026-07-30 16:27 UTCEPSS rescore
  21. 2026-07-30 03:08 UTCEG score recompute
  22. 2026-07-30 01:30 UTCEPSS rescore
  23. 2026-07-29 01:46 UTCEG score recompute
  24. 2026-07-28 15:36 UTCEPSS rescore
  25. 2026-07-27 18:07 UTCEG score recompute
  26. 2026-07-27 14:13 UTCEPSS rescore
  27. 2026-07-26 17:42 UTCEG score recompute
  28. 2026-07-26 14:54 UTCEPSS rescore
  29. 2026-07-26 14:54 UTCEPSS rescore
  30. 2026-07-25 14:17 UTCEPSS rescore
  31. 2026-07-24 14:17 UTCEPSS rescore
  32. 2026-07-23 14:18 UTCEPSS rescore
  33. 2026-07-23 03:04 UTCEG score recompute
  34. 2026-07-22 14:08 UTCEPSS rescore
  35. 2026-07-21 15:24 UTCEPSS rescore
  36. 2026-07-20 17:08 UTCEPSS rescore
  37. 2026-07-19 14:30 UTCEPSS rescore
  38. 2026-07-18 10:04 UTCEPSS rescore
  39. 2026-07-16 17:02 UTCEPSS rescore
  40. 2026-07-15 02:00 UTCEPSS rescore
  41. 2026-07-13 22:30 UTCEPSS rescore
  42. 2026-07-13 06:12 UTCEPSS rescore
  43. 2026-07-12 05:46 UTCEPSS rescore
  44. 2026-07-11 08:27 UTCEPSS rescore
  45. 2026-07-09 19:10 UTCEPSS rescore
  46. 2026-07-08 15:15 UTCEPSS rescore
  47. 2026-07-08 15:15 UTCEPSS rescore
  48. 2026-07-07 13:46 UTCEPSS rescore
  49. 2026-07-06 16:27 UTCEPSS rescore
  50. 2026-07-06 02:23 UTCEPSS rescore
  51. 2026-07-05 02:30 UTCEPSS rescore
  52. 2026-07-05 02:30 UTCEPSS rescore
  53. 2026-07-04 06:31 UTCEPSS rescore
  54. 2026-07-01 15:06 UTCEPSS rescore
  55. 2026-07-01 15:06 UTCEPSS rescore
  56. 2026-06-30 23:22 UTCEPSS rescore
  57. 2026-06-29 14:06 UTCEPSS rescore
  58. 2026-06-28 14:07 UTCEPSS rescore
  59. 2026-06-28 04:56 UTCEPSS rescore
  60. 2026-06-28 04:56 UTCEPSS rescore
  61. 2026-06-27 03:08 UTCEPSS rescore
  62. 2026-06-25 13:49 UTCEPSS rescore
  63. 2026-06-24 14:05 UTCEPSS rescore
  64. 2026-06-23 21:32 UTCEPSS rescore
  65. 2026-06-22 21:40 UTCEG score recompute▲ 9.30
  66. 2026-06-22 21:36 UTCNVD updateCVSS v3 → 9.3 · CVSS v4 → 9.3
  67. 2026-06-22 14:25 UTCEPSS rescore
  68. 2026-06-22 14:25 UTCEPSS rescore
  69. 2026-06-21 14:56 UTCEPSS rescore
  70. 2026-06-21 14:56 UTCEPSS rescore
  71. 2026-06-21 01:59 UTCEPSS rescore
  72. 2026-06-21 01:59 UTCEPSS rescore
  73. 2026-06-19 19:25 UTCEPSS rescore
  74. 2026-06-18 15:45 UTCEG score recompute
  75. 2026-06-18 15:45 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-11718?
CVE-2026-11718 is a critical vulnerability published on June 18, 2026. An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When the toolbox validates an opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), it decodes the response into an introspectResp struct. However,…
When was CVE-2026-11718 disclosed?
CVE-2026-11718 was first published in the National Vulnerability Database on June 18, 2026, with the most recent update on August 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-11718 actively exploited?
CVE-2026-11718 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 91.7% of all scored CVEs.
What is the CVSS score of CVE-2026-11718?
CVE-2026-11718 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-11718?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-11718, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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