CVE-2026-56278CWE-798

Flowise - Session Hijacking via Weak Default Express Session Secret

Critical · published June 30, 2026

CVSS v4.0
9.3
EPSS
1%
Percentile
43.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
9.3 · CRITICAL
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
EPSS
0.00528 · 43.9th percentile
Weakness
CWE-798 · Use of Hard-coded Credentials
Published
2026-06-30T22:08Z
EPSS history
Timeline
  • 30 JUN 22:08Z
    Flowise - Session Hijacking via Weak Default Express Session Secret
    cvelistv5