CVE-2026-12866

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-06-23. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

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

All versions of the package expr-eval are vulnerable to Code Execution via the toJSFunction() API. An attacker can execute arbitrary JavaScript by supplying crafted expressions that are compiled into native code using new Function(). Because user-controlled expressions are transformed directly into executable JavaScript, attackers can escape the intended expression sandbox and run arbitrary code within the application's context.

CVSS v3
9.8
EG Score
9.8(high)
EPSS
36.3%
KEV
Not listed

Published

June 23, 2026

Last Modified

July 7, 2026

Advisory Details (2)

Auto-updated Jun 29, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic🟡 PoC Available

Unsafe code execution in Node.js when using `toJSFunction()` with untrusted variables · Issue #292 · silentmatt/expr-eval · GitHub

https://github.com/silentmatt/expr-eval/issues/292
generic🔴 Active Exploitation

Code Execution in expr-eval | CVE-2026-12866 | Snyk

https://security.snyk.io/vuln/SNYK-JS-EXPREVAL-15054690

Vendor Advisories for CVE-2026-12866(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 82× in last 7d / 179× 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.

Showing the most recent 100 of 179 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-12866?
CVE-2026-12866 is a critical vulnerability published on June 23, 2026. All versions of the package expr-eval are vulnerable to Code Execution via the toJSFunction() API. An attacker can execute arbitrary JavaScript by supplying crafted expressions that are compiled into native code using new Function(). Because user-controlled expressions are transformed directly into…
When was CVE-2026-12866 disclosed?
CVE-2026-12866 was first published in the National Vulnerability Database on June 23, 2026, with the most recent update on July 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-12866 actively exploited?
CVE-2026-12866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 36.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-12866?
CVE-2026-12866 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-12866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-12866, 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.

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