Summary
CVE-2026-19297 is a critical vulnerability in IBM Langflow OSS caused by improper restriction of excessive authentication attempts (CWE-307) on the login endpoint. A remote, unauthenticated attacker can repeatedly attempt credentials against the login endpoint without being throttled or locked out, allowing brute-force access to user accounts. The issue carries a CVSS v3.1 base score of 9.1 (Critical).
Technical details
- Root cause: The Langflow OSS login endpoint does not enforce adequate protections (such as rate limiting or account lockout) against repeated authentication attempts.
- Trigger conditions: An attacker sends repeated login requests to the exposed login endpoint of an internet-facing Langflow OSS instance.
- Attack vector: Network-based, no privileges or user interaction required, low attack complexity.
- Impact: Successful brute forcing grants unauthorized access to user accounts, with high impact to confidentiality and integrity; there is no direct impact to availability.
Affected software
- IBM Langflow OSS versions 1.0.0 through 1.9.6
Severity
- CVSS v3.1 Base Score: 9.1 (Critical)
- Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Mitigation and recommended actions
- Immediate: Upgrade to Langflow OSS version 1.10.0 or later, available via PyPI. Version 1.10.0 introduces IP-based rate limiting on the
/loginendpoint, returning HTTP 429 with aRetry-Afterheader once a configured attempt threshold is exceeded. - If patching is not immediately possible: Restrict network exposure of the Langflow login endpoint (e.g., place it behind a VPN, IP allowlist, or reverse proxy with rate limiting/WAF rules), enforce strong, unique account passwords, and monitor authentication logs for repeated failed login attempts from the same source.
How IONIX identifies potentially affected assets
IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.
- Raw response body:
<title>Langflow</title>followed by a<script src="./assets/index-*.js">tag.

