Critical severity · published Jun 30, 2026
CVE-2026-56278
Flowise - Session Hijacking via Weak Default Express Session Secret
9.1
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 45% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FL
Flowise · Flowise
before 3.1.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56278
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-56278
Mitigation
https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-2qqc-p94c-hxwh
Third Party Advisory
https://www.vulncheck.com/advisories/flowise-session-hijacking-via-weak-default-express-session-secret
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