Mlflow: attackers can get in without a password
OFFICIAL NAME: Authentication Bypass in mlflow/mlflow
WHAT IT IS · DEVELOPER TOOLSIt holds source code and the keys used to build and ship software.
DO THIS FIRSTPatch it. If it faced the internet, change the keys and passwords stored in it. Not sure if you use it? Send this page to your IT provider or security lead and ask.
TECHNICAL SUMMARY A vulnerability in mlflow/mlflow versions 3.9.0 and earlier allows unauthenticated access to certain FastAPI routes when the server is started with authentication enabled (`--app-name basic-auth`) and served via uvicorn (ASGI).
WHY THIS VERDICT Attack attempts are confirmed, with no confirmed exploitation yet.
WHY IT RANKS HERE Ready-made attack tools are public. The first report is 20 days old.
- HIGHEST CONFIRMED RUNG
- TRIED
- CISA KEV
- NOT YET
- EXPLOIT CODE
- READY TO USE
How far has it climbed?
01 TALK
□ NO EVIDENCE YETNEWEST EVIDENCE NONE YETNo evidence yet.
SRC: NONE YET02 EXPOSED
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETWe have no source that counts exposed systems yet. Internet scan data needs a partnership we do not have. No evidence here does not mean nothing is exposed.
03 TRIED
■ CONFIRMEDNEWEST EVIDENCE · 1 SOURCEAttack attempts on CVE-2026-2652 seen by honeypots (Shadowserver via CIRCL). Attack attempts on CVE-2026-2652 seen by honeypots (Shadowserver via CIRCL).
04 EXPLOITED
□ NO EVIDENCE YETNEWEST EVIDENCE NONE YETNo evidence yet.
SRC: NONE YET05 DAMAGE
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETBreach notices and filings rarely name the flaw that was used, so we cannot link them to this event yet. No evidence here does not mean no harm.
When each thing happened
- DISCLOSED
- EXPLOIT CODE PUBLICDATE UNKNOWN
- FIRST ATTACK REPORT
- CISA KEV LISTINGNOT YET
- US FEDERAL DEADLINENOT YET
Questions to ask this week
- Do we run Mlflow? If yes, is it patched or cut off from the internet?
- Who owns fixing it, and by what date?
- Have we checked for signs of attack since the first report, not just since the patch?
How it unfolded
- MAY 14, 2026CISA Vulnrichment notes a public proof of concept for CVE-2026-2652
- Attack activity. OCT 21, 2026Attack attempts on CVE-2026-2652 seen by honeypots (Shadowserver via CIRCL) (2 reports, latest OCT 22)
SOURCES
- [1] nuclei-templates: Nuclei scan template: MLflow < 3.10.0 - Authentication Bypass on FastAPI Routes, OCT 24
- [2] CIRCL Vulnerability-Lookup sightings: Attack attempts on CVE-2026-2652 seen by honeypots (Shadowserver via CIRCL), OCT 22
- [3] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment notes a public proof of concept for CVE-2026-2652, MAY 14