CVE-2026-56278: 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 envi

criticalCVSS 9.1CVE-2026-56278

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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: critical — CVSS 9.1
Published: 2026-06-30
Last updated: 2026-07-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-56278

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-562780.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 28% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-56278	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[UPDATE] [high] Flowise: Multiple vulnerabilitiescert-bund

Recent advisories for Flowise

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

critical[UPDATE] [critical] Flowise: Multiple vulnerabilitiescert-bund · 2026-07-10
high[UPDATE] [high] Flowise: Multiple vulnerabilitiescert-bund · 2026-07-09
mediumCVE-2026-56273: Flowise before 3.1.0 contains a path traversal vulnerability in Faiss and SimpleStore vector s…nvd · 2026-07-08
mediumCVE-2026-56277: Flowise before 3.1.2 sets Access-Control-Allow-Origin to a hardcoded wildcard (*) on its text-…nvd · 2026-06-30
mediumCVE-2026-58057: Flowise before 3.1.3 validates Custom MCP stdio environment variables against a denylist using…nvd · 2026-06-28
criticalCVE-2025-71338: Flowise contains a path traversal vulnerability in the /api/v1/document-store/loader/process e…nvd · 2026-06-25