CVE-2026-55255: Langflow Authorization Bypass Through User-Controlled Key Vulnerability
What it is
Langflow contains an authorization bypass through user-controlled key vulnerability which allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.
What to do
Schedule the vendor fix into this week’s change window, prioritising internet-facing and business-critical systems. Confirm the fix is applied everywhere, not just where it was easy.
- Priority
- This week: Schedule into this week’s change window.
- Severity (CVSS)
- 8.4 high
- CISA assessment (SSVC)
- actively exploited; needs manual effort per target; total control of the affected system
- Exploit probability (EPSS, 30 days)
- 0.9%, higher than 58% of all CVEs
- Added to CISA KEV
- 7 July 2026
- CISA fix-by date
- 10 July 2026 (US federal agencies; a sensible deadline for everyone)
- Ransomware use
- Not known
- Weakness
- CWE-639
References
- NIST NVD entry
- CISA KEV entry
- github.com/langflow-ai/langflow/commit/2c9f498d664a3c32698b57d7c5e752625291060e
- github.com/langflow-ai/langflow/pull/12832
- github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
- github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
- webflow.sysdig.com/blog/understanding-langflow-cve-2026-55255-and-why-higher-cvs
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55255
Sources: CISA Known Exploited Vulnerabilities · FIRST Exploit Prediction Scoring System (EPSS) · NIST National Vulnerability Database · CISA Vulnrichment (SSVC), via the CVE Program. This product uses data from the NVD API but is not endorsed or certified by the NVD. Summaries are machine-written from CISA’s description; treat the vendor’s advisory as the authority for fixes.