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HIGH

CVE-2026-86076

CVE-2026-86076 — n8n: Expression Sandbox Escape in Editor-UI Enables Stored Cross-User JavaScript Execution

n8n is an open source workflow automation platform. Prior to 1.123.76, 2.37.7, and 2.38.2, the expression compiler sanitizer resolved through dynamically scoped this and did not reject reserved class member names. A class field named __sanitize could rebind the sanitizer and reach the Function constructor, enabling backend code execution and editor-preview JavaScript execution. The affected AST hook is PrototypeSanitizer in packages/workflow/src/expression-sandboxing.ts. This issue is fixed in versions 1.123.76, 2.37.7 and 2.38.2.

Published Updated Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

0%

chance of exploitation in 30 days

Affects

n8n io

n8n

CVSS base

8.7

HIGH

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

n8n io

Products (1)

n8n

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
8.7CVSS 4.0HIGH——cvelistV5

Weakness & attack patterns

  • CWE-94

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1027.006Obfuscated Files or Information: HTML Smuggling
  • T1027.009Obfuscated Files or Information: Embedded Payloads
  • T1564.009Hide Artifacts: Resource Forking

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

  • Search application, proxy, and WAF logs for requests touching /workflow/src/expression-sandboxing.ts.

References

4 on the record

Elsewhere on this site

  • n8n ioevery CVE for this vendor
  • CWE-94other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.