CVE-2026-63376

HIGHPre-NVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% 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, secondary
Elevated
8.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.2Exploit: Elevated riskExposed: 0

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

toml-node is a TOML parser for Node.js and the browser. Prior to 4.1.2, toml.parse() in lib/compiler.js can be tricked by a table path such as a.b.y.__proto__.__proto__, allowing traversal from a scalar value into Number.prototype and Object.prototype. The currentPath tracking value uses both arrays and strings, so valueAssignments records a comma-joined path such as a,b.y while deepRef checks the dot-joined path a.b.y, allowing the duplicate-key guard to miss and attacker-controlled keys to be written to Object.prototype. A table-array prefix-clearing path in addTableArray can also erase guard state before the same __proto__ traversal. Injected properties become visible throughout the Node.js process and can cause denial of service, logic or authorization bypass, or code execution when an application contains a suitable gadget. This issue is fixed in version 4.1.2.

CVSS v3
8.2
EG Score
8.2(medium)
EG Risk
68(Attend)
EG Risk 68/100SSVC: Attend

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
Severity82% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

September 3, 2026

Last Modified

September 9, 2026

Advisory Details (3)

Auto-updated Sep 3, 2026
Patch available. Sources: github, github_commit.
github_commit

commit dfaff662276a (BinaryMuse/toml-node)

Fix landed in BinaryMuse/toml-node commit dfaff662276a — awaiting tagged release

https://github.com/BinaryMuse/toml-node/commit/dfaff662276adc38a2e03df3139f7119b0185463
github_commit

commit def6ab5ea990 (BinaryMuse/toml-node)

Fix landed in BinaryMuse/toml-node commit def6ab5ea990 — awaiting tagged release

https://github.com/BinaryMuse/toml-node/commit/def6ab5ea99038c0dd482cd6af1745a6af8b4c44
github Patch Available

Prototype Pollution Leads to `Object.prototype` Corruption via `__proto__` Key-Path Desynchronization · Advisory · BinaryMuse/toml-node · GitHub

https://github.com/BinaryMuse/toml-node/security/advisories/GHSA-v5mp-jgw5-2x6j

Vendor Advisories for CVE-2026-63376(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)
npm(1)
PackageVulnerable rangeFixed inDependents
toml—4.1.2—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 29× 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. 2026-09-19 20:07 UTCEG score recompute
  2. 2026-09-18 21:23 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 22:10 UTCEG score recompute
  5. 2026-09-16 23:24 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 12:03 UTCEG score recompute
  8. 2026-09-16 05:15 UTCEPSS rescore
  9. 2026-09-15 13:20 UTCEG score recompute
  10. 2026-09-14 03:17 UTCEG score recompute
  11. 2026-09-12 17:16 UTCEG score recompute
  12. 2026-09-11 18:34 UTCEG score recompute
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 09:37 UTCEPSS rescore
  15. 2026-09-10 19:52 UTCEG score recompute
  16. 2026-09-08 23:06 UTCEG score recompute
  17. 2026-09-08 22:01 UTCEPSS rescore
  18. 2026-09-07 23:36 UTCEG score recompute
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-07 00:51 UTCEG score recompute
  21. 2026-09-06 13:47 UTCEPSS rescore
  22. 2026-09-06 02:07 UTCEG score recompute
  23. 2026-09-05 15:31 UTCEPSS rescore
  24. 2026-09-05 03:23 UTCEG score recompute
  25. 2026-09-05 02:30 UTCEG score recompute
Show 4 more
  1. 2026-09-04 20:07 UTCEG score recompute
  2. 2026-09-03 21:21 UTCEG score recompute
  3. 2026-09-03 20:39 UTCEG score recompute
  4. 2026-09-03 20:38 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63376?
CVE-2026-63376 is a high vulnerability published on September 3, 2026. toml-node is a TOML parser for Node.js and the browser. Prior to 4.1.2, toml.parse() in lib/compiler.js can be tricked by a table path such as a.b.y.proto.proto, allowing traversal from a scalar value into Number.prototype and Object.prototype. The currentPath tracking value uses both arrays and…
When was CVE-2026-63376 disclosed?
CVE-2026-63376 was first published in the National Vulnerability Database on September 3, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63376 actively exploited?
CVE-2026-63376 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 67.8% of all scored CVEs.
What is the CVSS score of CVE-2026-63376?
CVE-2026-63376 has a CVSS v3 base score of 8.2 (NVD).
How do I remediate CVE-2026-63376?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63376, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63376

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