On July 7, 2026, the U.S. CISA added CVE-2026-55255, an authorization bypass vulnerability in the AI workflow builder Langflow, to its Known Exploited Vulnerabilities (KEV) Catalog and ordered federal agencies to patch it by July 10.
July 7, 2026 · CISA Known Exploited Vulnerabilities
Critical Langflow Flaw Added to CISA KEV — Federal Agencies Given 3 Days to Patch
CVE-2026-55255 is an authorization-bypass (IDOR) flaw in the popular AI workflow builder Langflow, letting an authenticated attacker run flows owned by other users. CISA ordered a patch by July 10.
9.9
CVSS v3.1 score — rated Critical
3 days
from KEV listing (Jul 7) to patch deadline (Jul 10)
140k+
GitHub stars — self-hosted AI agent tool
< 1.9.1
affected versions — fixed in 1.9.1+
Why priority gets underestimated: CVSS vs. real exploitability
A higher CVSS isn't always the most exploited. This flaw requires authentication, raising the bar — but it was chained behind an unauthenticated RCE in the wild.
RCE
CVE-2026-33017primary vector
+
IDOR
CVE-2026-55255supplement
Taller column = fewer barriers to exploit. Unauthenticated RCE clears the bar first; the IDOR flaw amplifies access afterward.
The exploitation chain
1 · Enumerate
List target flow IDs via /api/v1/flows/
→
2 · Bypass
No ownership check in get_flow_by_id
→
3 · Execute
Run others' flows via /api/v1/responses
Recommended actions
Update to Langflow 1.9.1 or later
Block unnecessary external exposure
Review and enforce authentication settings
Ongoing concern
Highest risk in shared multi-tenant instances
Authentication often disabled by default
Security lagging behind rapid adoption
First active exploitation was observed on June 25, 2026 . KEV entries serve as a patching benchmark not only for federal agencies but also for private companies and state and local governments — if remediation isn't completed in time, discontinuing use of the product is among the options.
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