CVE-2026-119978 (CVSS 8.5)

Description

Flowise through 3.1.4 contains a sandbox escape vulnerability that allows authenticated users to execute OS commands by abusing allowlisted langchain and mammoth modules when ALLOW_BUILTIN_DEP=true. Attackers can submit JavaScript to /api/v1/node-custom-function that writes a file into the mammoth package via LocalFileStore and requires it, escaping vm2 as the Flowise process user.

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CVSS v3.1 Score

8.5

HIGH

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0034

Probability of exploitation

0.28%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-749 CWE-749

References

Other References

https://github.com/FlowiseAI/Flowise https://github.com/FlowiseAI/Flowise/blob/a65f81bb43ef66d3ce734bf0dff4223ae8041c95/packages/components/src/utils.ts#L1733 https://github.com/FlowiseAI/Flowise/blob/a65f81bb43ef66d3ce734bf0dff4223ae8041c95/packages/components/src/utils.ts#L55-L114 https://github.com/advisories/GHSA-9gvv-qjj3-2p6g https://www.vulncheck.com/advisories/flowise-through-3.1.4-custom-function-sandbox-escape-rce-via-localfilestore

Frequently Asked Questions

What is CVE-2026-119978? +

Flowise through 3.1.4 contains a sandbox escape vulnerability that allows authenticated users to execute OS commands by abusing allowlisted langchain and mammoth modules when ALLOW_BUILTIN_DEP=true. Attackers can submit JavaScript to /api/v1/node-custom-function that writes a file into the mammoth package via LocalFileStore and requires it, escaping vm2 as the Flowise process user. It has a CVSS v3.1 base score of 8.5 (HIGH).

How severe is CVE-2026-119978? +

CVE-2026-119978 has a CVSS v3.1 score of 8.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0034, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-119978? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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