mlflow/mlflow: Authentication Bypass by Primary Weakness
CVE-2026-2652 is a high-severity authentication bypass by primary weakness vulnerability in mlflow/mlflow from Mlflow, with a CVSS 3.0 base score of 8.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 3.10.0 as the first without the flaw, so updating mlflow/mlflow to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 20.8% chance of exploitation within 30 days, which is in the top 2.42% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update mlflow/mlflow to 3.10.0 or a later version.
- Update Mlflow to 3.10.0 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Mlflow | mlflow/mlflow | before 3.10.0 | 3.10.0 |
| Lfprojects | Mlflow | before 3.10.0 | 3.10.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- LowSome restricted data can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L. Scored by CNA (huntr.dev).
Official description
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). The FastAPI permission middleware only enforces authentication on `/gateway/` routes, leaving other routes such as the Job API (`/ajax-api/3.0/jobs/*`) and the OpenTelemetry trace ingestion API (`/v1/traces`) unprotected. This allows unauthenticated remote attackers to submit jobs, read job results, cancel running jobs, and inject arbitrary trace data into experiments. The issue arises from an architectural mismatch between Flask and FastAPI authentication mechanisms, where the `_find_fastapi_validator()` function fails to handle non-`/gateway/` paths, resulting in a complete authentication bypass. This vulnerability is fixed in version 3.10.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass by Primary Weakness
The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.
More Authentication Bypass by Primary Weakness vulnerabilities (CWE-305)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/mlflow/mlflow/commit/bb62e773263c14e9ba4d1a82fe72d0de2442c6aa
- huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756Exploit, Mitigation, Third Party Advisory
Other vulnerabilities in mlflow/mlflow
- 8.1 High severity
- 7.7 High severity
- 9.0 Critical severity
- 9.6 Critical severity
- 7.8 High severity
- 7.5 High severity
Recent Authentication Bypass by Primary Weakness vulnerabilities
- 8.3 High severity
- 9.8 Critical severity
- 7.1 High severity
- 8.1 High severity
- 9.8 Critical severity
- 8.8 High severity
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