Flowise - Session Hijacking via Weak Default Express Session Secret
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-798.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Flowise (Flowise) Fixed in 3.1.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-56278
- 2026-10-03 Alias added: GHSA-c973-v3cg-wcw4
References
More FlowiseAI Flowise vulnerabilities
- TI-2025-37059 Flowise has Remote Code Execution vulnerability CVSS 3.1CRITICAL 10.0
- TI-2025-36193 Flowise Cloud and Local Deployments have Unauthenticated Password Reset Token Disclosure that Leads to Account Takeover CVSS 3.1CRITICAL 9.8
- TI-2025-08190 Unsupervised OS command execution leads to remote code execution by unauthenticated network attackers CVSS 3.1CRITICAL 9.8
- TI-2026-51595 Flowise before 3.1.3 Sandbox Escape via Puppeteer CVSS 4.0CRITICAL 9.4
- TI-2026-49250 Flowise: CSV Agent Prompt Injection Remote Code Execution Vulnerability CVSS 4.0CRITICAL 9.5
- TI-2025-43459 Flowise through 2.2.7 - Arbitrary File Write to Remote Code Execution via document-store API CVSS 4.0CRITICAL 10.0
Sources
- CVE-2026-56278 · CVE Program
- CVE-2026-56278 · NVD
- FIRST EPSS
- GHSA-c973-v3cg-wcw4 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences