CVE-2026-56278: Flowise - Session Hijacking via Weak Default Express Session Secret

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-30 · updated 2026-07-06
Weakness: CWE-798

Description

Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses a weak hardcoded default secret ('flowise') for the express-session middleware when the EXPRESS_SESSION_SECRET environment variable is not set (packages/server/src/enterprise/middleware/passport/index.ts). Because this default secret is publicly visible in the source code, an attacker can forge valid signed session cookies to impersonate any user and bypass authentication.

Affected products

FlowiseAI Flowise: before 3.1.0 — fixed in 3.1.0

How to fix

Upgrade to a fixed version: FlowiseAI Flowise 3.1.0. Check the vendor advisory for mitigations.

References

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