Critical Authentication

CVE-2026-54309 — n8n @n8n/mcp-browser: missing authentication on HTTP MCP endpoint

n8n is an open source workflow automation platform. Prior to 2.25.7 and 2.26.2, when @n8n/mcp-browser is run in HTTP transport mode, the MCP endpoint accepts session initialization and tool invocation requests without any authentication. Any network-reachable client, or any website visited by the user, can establish an MCP session and invoke browser-control tools. Where the n8n AI Browser Bridge extension is installed and a browser connection is active, an unauthenticated caller can access browser-control capabilities including navigation, JavaScript evaluation, and cookie and storage access against the user's real browser profile. This issue only affects instances where @n8n/mcp-browser is run with the HTTP transport (--transport http). This vulnerability is fixed in 2.25.7 and 2.26.2.

Published Jun 23, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.5% (30-day exploitation probability)+7
Technical severity (critical)+10
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

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

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.55%

ahead of 44% of scored CVEs · Oct 14, 2026

Affects

N8n

CVSS base

10.0

Critical · 3 source(s)

CISA SSVC assessment CISA

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

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented mitigation — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (N8n N8n, N8n-io N8n).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the documented mitigations until a definitive fix is available.
Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
N8n	N8n	< 2.25.7≥ 2.26.0 and < 2.26.2	Vulnerable	NIST National Vulnerability Database
N8n-io	N8n	version >= 2.26.0, < 2.26.2version < 2.25.7	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

Low

Every base score collected

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

Score	Version	Severity	Expl.	Impact	Scored by
8.8	CVSS 4.0	High	—	—	security-advisories@github.com via NIST National Vulnerability Database
8.8	CVSS 4.0	High	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
10.0	CVSS 3.1	Critical	3.9	6.0	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-306 · Missing Authentication for Critical Function

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.55%

Detection

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

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.

web/proxy/WAF logsnetwork IDS/IPSauthentication logs

Analysis and videos

CVE-2026-54309: n8n @n8n/mcp-browser: missing authentication on HTTP MCP endpoint
The @n8n/mcp-browser package of n8n, when run with the HTTP transport, exposes an MCP endpoint that accepts session initialization and tool calls without authentication, a weakness classified as CWE-306. Where the n8n AI Browser Bridge extension is installed and connected, an unauthenticated caller could reach browser-control functions on the user's real browser profile. The vendor fixes are in versions 2.25.7 and 2.26.2, and the record shows no CISA KEV listing.

Timeline

What happened to this CVE, newest first.

2026
Affected products added · n8n-io/n8n
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 10.0
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Jun 23, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

github.com/n8n-io/n8n/security/advisories/GHSA-qrx8-25qr-5r7v
Mitigation, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

N8n
every CVE for this vendor

Authentication
same class

CWE-306
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-110853 n8n before 1.123.83 Authorization Bypass via Execute Sub-workflow Inline JSON 1d
Medium CVE-2026-110851 n8n before 2.41.4 and 2.42.1 Cross-Project Agent Ownership Transfer via Agents Create Endpoint 1d
Medium CVE-2026-110852 n8n before 1.123.83, 2.41.4, and 2.42.1 Unauthenticated Workflow Execution via Dynamic-Path Webhook Resolution 1d
Medium CVE-2026-110848 n8n before 1.123.83, 2.41.4, and 2.42.1 Prototype Pollution via AI Workflow Builder Connection Merge 1d
High CVE-2026-110847 n8n before 1.123.83, 2.41.4, and 2.42.1 Stored XSS via Chat Trigger customCss Parameter 1d
High CVE-2026-110850 n8n before 2.41.4 and 2.42.1 Credential Check Bypass via Agent Node Parameters 1d

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.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-54309 is "n8n @n8n/mcp-browser: missing authentication on HTTP MCP endpoint", rated Critical. It affects N8n (N8n); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 10.0 describes technical severity. EPSS 0.55% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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