MLflow - SSRF (CVE-2026-64849)

CVE-2026-64849 is a critical server-side request forgery (SSRF) vulnerability in MLflow versions prior to 3.15.0. An unauthenticated attacker can exploit the webhook testing endpoint to bypass URL validation through redirects and DNS re-resolution, accessing internal services or cloud metadata endpoints and retrieving response data. This could expose sensitive credentials and information, with potential limited impact on internal service integrity.

CrowdSec has been tracking this vulnerability and its exploits since 25th of August 2026.

Insights from the CrowdSec network reveal that the attackers trying to exploit CVE-2026-64849 are composed of a fairly even mix of opportunistic and targeted actors. Some attackers employ preliminary reconnaissance, while others use indiscriminate scanning. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2026-64849 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2026-64849 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attackers target MLflow’s webhook API by creating a webhook through /api/2.0/mlflow/webhooks with an attacker-controlled or internal URL, then invoking /api/2.0/mlflow/webhooks/{webhook_id}/test to trigger server-side requests and observe the response through an external callback.