CVE-2026-56271
Flowise - Weak Default JWT Secrets in Authentication Middleware
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT secrets ('auth_token', 'refresh_token') and default audience and issuer values ('AUDIENCE', 'ISSUER') in the enterprise passport authentication middleware (packages/server/src/enterprise/middleware/passport/index.ts). When the corresponding environment variables (JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER) are not set, the application silently falls back to these publicly known defaults, allowing an attacker to forge valid JWTs and impersonate any user, including administrators, resulting in authentication bypass.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
9.3
Flowise - Weak Default JWT Secrets in Authentication Middleware
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT secrets ('auth_token', 'refresh_token') and default audience and issuer values ('AUDIENCE', 'ISSUER') in the enterprise passport authentication middleware (packages/server/src/enterprise/middleware/passport/index.ts). When the corresponding environment variables (JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER) are not set, the application silently falls back to these publicly known defaults, allowing an attacker to forge valid JWTs and impersonate any user, including administrators, resulting in authentication bypass.
- Record
CVE-2026-56271- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-321
- Updated
- 2026-11-02
EUVDEUVD-2026-43228
9.3
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT secrets ('auth_token', 'refresh_token') and default audience and issuer values ('AUDIENCE', 'ISSUER') in the enterprise passport authentication middleware (packages/server/src/enterprise/middleware/passport/index.ts). When the corresponding environment variables (JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER) are not set, the application silently falls back to these publicly known defaults, allowing an attacker to forge valid JWTs and impersonate any user, including administrators, resulting in authentication bypass.
- Record
EUVD-2026-43228- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-cc4f-hjpj-g9p8
5.6
Flowise: Weak Default JWT Secrets
Detection Method: Kolega.dev Deep Code Scan
| Attribute | Value | |---|---| | Severity | Critical | | Location | packages/server/src/enterprise/middleware/passport/index.ts:29-34 | | Practical Exploitability | High | | Developer Approver | [email protected] |
Description
JWT secrets have weak hardcoded defaults ('auth_token', 'refresh_token', 'AUDIENCE', 'ISSUER'). Attackers can forge valid JWTs and impersonate any user.
Affected Code
const jwtAudience = process.env.JWT_AUDIENCE || 'AUDIENCE'
const jwtIssuer = process.env.JWT_ISSUER || 'ISSUER'
const jwtAuthTokenSecret = process.env.JWT_AUTH_TOKEN_SECRET || 'auth_token'
const jwtRefreshSecret = process.env.JWT_REFRESH_TOKEN_SECRET || process.env.JWT_AUTH_TOKEN_SECRET || 'refresh_token'
Evidence
All JWT defaults are weak strings. Refresh token falls back to auth token which is a design flaw. If any environment variable is unset, weak default is used.
Impact
Complete authentication bypass. Attackers can forge valid JWTs for any user account. No authentication required to access protected endpoints. Can escalate to admin access.
Recommendation
Remove all default secrets - require all JWT environment variables to be explicitly set. Add startup validation throwing error if any JWT secret is missing. Use cryptographically random secrets (256+ bits) for each secret independently. Implement JWT secret rotation mechanism.
Notes
The JWT secrets have genuinely weak hardcoded defaults ('auth_token', 'refresh_token', 'AUDIENCE', 'ISSUER') at lines 29-34. If an administrator deploys without setting the environment variables JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, and JWT_ISSUER, the application will use these trivially guessable values. An attacker knowing these defaults (which are publicly visible in the source code) can forge valid JWTs to impersonate any user, including administrators. The fallback chain at line 34 where jwtRefreshSecret falls back to jwtAuthTokenSecret is an additional design weakness - if only JWT_AUTH_TOKEN_SECRET is set, both tokens share the same secret. While .env.example files provide placeholder values, these are also weak and publicly visible. The application should fail to start if these secrets are not explicitly configured with strong values, rather than silently falling back to insecure defaults.
- Record
GHSA-cc4f-hjpj-g9p8- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-327
- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-jpvq-qwhh-pw47
9.3
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT...
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT secrets ('auth_token', 'refresh_token') and default audience and issuer values ('AUDIENCE', 'ISSUER') in the enterprise passport authentication middleware (packages/server/src/enterprise/middleware/passport/index.ts). When the corresponding environment variables (JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER) are not set, the application silently falls back to these publicly known defaults, allowing an attacker to forge valid JWTs and impersonate any user, including administrators, resulting in authentication bypass.
- Record
GHSA-jpvq-qwhh-pw47- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-321
- Updated
- 2026-11-02
NVD
9.3
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT secrets ('auth_token', 'refresh_token') and default audience and issuer values ('AUDIENCE', 'ISSUER') in the enterprise passport authentication middleware (packages/server/src/enterprise/middleware/passport/index.ts). When the corresponding environment variables (JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER) are not set, the application silently falls back to these publicly known defaults, allowing an attacker to forge valid JWTs and impersonate any user, including administrators, resulting in authentication bypass.
- Record
CVE-2026-56271- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-321
- Updated
- 2026-11-02
OSV
9.3
Flowise - Weak Default JWT Secrets in Authentication Middleware
Flowise before 3.1.0 (affected versions 3.0.13 and earlier) uses weak hardcoded default JWT secrets ('auth_token', 'refresh_token') and default audience and issuer values ('AUDIENCE', 'ISSUER') in the enterprise passport authentication middleware (packages/server/src/enterprise/middleware/passport/index.ts). When the corresponding environment variables (JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER) are not set, the application silently falls back to these publicly known defaults, allowing an attacker to forge valid JWTs and impersonate any user, including administrators, resulting in authentication bypass.
- Record
CVE-2026-56271- CVSS 4.0
- 9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-321
- Updated
- 2026-11-02
OSVGHSA-cc4f-hjpj-g9p8
5.6
Flowise: Weak Default JWT Secrets
Detection Method: Kolega.dev Deep Code Scan
| Attribute | Value | |---|---| | Severity | Critical | | Location | packages/server/src/enterprise/middleware/passport/index.ts:29-34 | | Practical Exploitability | High | | Developer Approver | [email protected] |
Description
JWT secrets have weak hardcoded defaults ('auth_token', 'refresh_token', 'AUDIENCE', 'ISSUER'). Attackers can forge valid JWTs and impersonate any user.
Affected Code
const jwtAudience = process.env.JWT_AUDIENCE || 'AUDIENCE'
const jwtIssuer = process.env.JWT_ISSUER || 'ISSUER'
const jwtAuthTokenSecret = process.env.JWT_AUTH_TOKEN_SECRET || 'auth_token'
const jwtRefreshSecret = process.env.JWT_REFRESH_TOKEN_SECRET || process.env.JWT_AUTH_TOKEN_SECRET || 'refresh_token'
Evidence
All JWT defaults are weak strings. Refresh token falls back to auth token which is a design flaw. If any environment variable is unset, weak default is used.
Impact
Complete authentication bypass. Attackers can forge valid JWTs for any user account. No authentication required to access protected endpoints. Can escalate to admin access.
Recommendation
Remove all default secrets - require all JWT environment variables to be explicitly set. Add startup validation throwing error if any JWT secret is missing. Use cryptographically random secrets (256+ bits) for each secret independently. Implement JWT secret rotation mechanism.
Notes
The JWT secrets have genuinely weak hardcoded defaults ('auth_token', 'refresh_token', 'AUDIENCE', 'ISSUER') at lines 29-34. If an administrator deploys without setting the environment variables JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, and JWT_ISSUER, the application will use these trivially guessable values. An attacker knowing these defaults (which are publicly visible in the source code) can forge valid JWTs to impersonate any user, including administrators. The fallback chain at line 34 where jwtRefreshSecret falls back to jwtAuthTokenSecret is an additional design weakness - if only JWT_AUTH_TOKEN_SECRET is set, both tokens share the same secret. While .env.example files provide placeholder values, these are also weak and publicly visible. The application should fail to start if these secrets are not explicitly configured with strong values, rather than silently falling back to insecure defaults.
- Record
GHSA-cc4f-hjpj-g9p8- CVSS 3.1
- 5.6 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-327
- Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-56271 is a critical vulnerability (CVSS 9.3) in Flowise, published April 16, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.66%, the 51st percentile. Fixed in flowise 3.1.0.
References
github.com/FlowiseAI/Flowise/security/advisories/GHSA-cc4f-hjpj-g9p8
vulncheck.com/advisories/flowise-weak-default-jwt-secrets-in-authentication-middleware
github.com/advisories/GHSA-cc4f-hjpj-g9p8
nvd.nist.gov/vuln/detail/CVE-2026-56271
github.com/advisories/GHSA-jpvq-qwhh-pw47
github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56271.json
github.com/FlowiseAI/Flowise