CVE-2026-56278

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 v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0038

Probability of exploitation

0.30%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-798 CWE-798

Affected Products

Vendor	Product	Versions
flowiseai	flowise	< 3.1.0

References

Advisories & Patches

https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-2qqc-p94c-hxwh

Other References

https://www.vulncheck.com/advisories/flowise-session-hijacking-via-weak-default-express-session-secret

Frequently Asked Questions

What is 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 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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-56278? +

CVE-2026-56278 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0038, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-56278? +

CVE-2026-56278 affects products from flowiseai, specifically: flowise. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-56278? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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