n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code…
n8n
- Severity
- High, CVSS 8.8
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Record
- CVE-2026-86083
- Affects
- n8n
- Known exploited
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- September 8, 2026
- Source last modified
- September 11, 2026
Description
n8n is an open source workflow automation platform. Prior to 1.123.76, 2.37.7, and 2.38.2, the legacy expression engine generated source text by calling the mutable global JSON.stringify while printing synthetic string literals and interpolating timezone data. An expression could replace JSON.stringify and cause later generated source to contain executable attacker-controlled code. The affected code-generation paths include packages/@n8n/expression-runtime/src/bridge/isolated-vm-bridge.ts and packages/@n8n/tournament/src/ExpressionBuilder.ts, and the issue does not affect the vm expression engine. This issue is fixed in versions 1.123.76, 2.37.7 and 2.38.2.
Description quoted from the NVD record.
Who is affected
n8n is a tool for automating tasks by linking apps and services together into workflows. This flaw affects versions before 1.123.76, 2.37.7 and 2.38.2. It only affects setups that use the older (legacy) engine that works out expressions, the small formulas placed inside workflows. The other engine, called the vm expression engine, is not affected. A carefully written expression could tamper with a shared part of that older engine so that code chosen by the attacker can run. This flaw is rated High.
What to do
- If your organization runs n8n itself, the person who installed or looks after it should check which version is in use.
- If that version is earlier than 1.123.76, 2.37.7 or 2.38.2, update it to
1.123.76,2.37.7or2.38.2, whichever is closest to the version you run now. - If an IT provider or vendor runs n8n for your organization, send them this advisory and ask when the update will be done.
- If you are not sure whether anyone in your organization uses n8n, ask the people who set up automated tasks, and pass this advisory to whoever looks after it.
Analysis written from the source record as of September 11, 2026 and reviewed before publishing.