n8n before 2.39.6 and 2.40.x before 2.40.1 Session Token Leak via Dynamic Credentials (CVE-2026-103259) | HOL Guard CVE

High · CVSS 8.5CVE-2026-103259

n8n before 2.39.6 and 2.40.x before 2.40.1 Session Token Leak via Dynamic Credentials

Answer in brief

CVE-2026-103259 records a High severity (CVSS 8.5) vulnerability in n8n before 2.39.6 and 2.40.x before 2.40.1 Session Token Leak via Dynamic Credentials. The current sources do not mark it as known exploited. The current feed maps n8n-io/n8n (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 1, 2026Updated Oct 1, 2026Source checked Oct 1, 2026First seen by HOL Oct 1, 2026Material review Oct 1, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 8.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps n8n-io/n8n (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
n8n-io/n8ngeneric	>=0 <2.39.6 \|\| >=2.40.0 <2.40.1	2.39.6, 2.40.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for n8n-io/n8n.
Review the reported fix. Update n8n-io/n8n to 2.39.6 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 1, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 1, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 1, 2026

Sources and claim methodology

Upstream source description

n8n versions before 2.39.6 and 2.40.0 before 2.40.1 contain a session token leakage vulnerability in the Dynamic Credentials authorize and revoke endpoints. Attackers with resolver registration capability can capture collaborators' session tokens by setting a fallback resolver to an attacker-controlled endpoint during the account connection flow, enabling unauthorized credential access.

Quoted source text, attributed separately from HOL analysis.