CVE-2026-118678

n8n before 2.41.4 and 2.42.1 Prototype Pollution DoS via Workflow History Compaction

State: Published
Severity: 7.1 High
Published: Oct 28, 2026
Updated: Oct 29, 2026
Reserved: Oct 28, 2026

Description

n8n before 2.41.4 and 2.42.x before 2.42.1 contains a prototype pollution vulnerability that allows low-privileged users to alter built-in object behaviour by saving workflows with specially named connection keys. Attackers can add keys such as __proto__ to workflow connections, which the periodic history compaction task processes, causing logins and writes to fail with server errors.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N	VulnCheck
3.1	7.1 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H	VulnCheck

Weaknesses

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Affected Products

Product	Versions
n8nn8n-io	before 2.41.4Affected 2.41.4Not affected
n8nn8n-io	2.42.0 to before 2.42.1Affected 2.42.1Not affected

References

GitHub Security Advisory (GHSA-fvv4-gmv9-xqf5)vendor-advisory
VulnCheck Advisory: n8n before 2.41.4 and 2.42.1 Prototype Pollution DoS via Workflow History Compactionthird-party-advisory

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