mlflow/mlflow: Insertion of Sensitive Information Into Sent Data
CVE-2026-4035 is a high-severity insertion of sensitive information into sent data vulnerability in mlflow/mlflow from Mlflow, with a CVSS 3.1 base score of 7.7 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 3.11.0 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 0.52% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update mlflow/mlflow to 3.11.0 or a later version.
- Update Mlflow to 3.11.0 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Mlflow | mlflow/mlflow | before 3.11.0 | 3.11.0 |
| Red Hat | Red Hat OpenShift AI (RHOAI) | Not specified in the record | Not stated |
| Lfprojects | Mlflow | before 3.11.0 | 3.11.0 |
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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.7 | High | NVD |
| CVSS 3.1 | 7.7 | High | CNA |
| CVSS 3.0 | 9.1 | Critical | CNA (huntr.dev) |
Official description
A vulnerability in mlflow/mlflow versions prior to 3.11.0 allows for the resolution of environment variables in AI Gateway secrets, which can be exploited to exfiltrate sensitive server-side environment credentials to an attacker-controlled endpoint. This issue arises because the `api_key` field in gateway secrets can accept `$ENV_VAR` references, which are resolved against the MLflow server's environment during runtime. The resolved secrets are then sent in provider authentication headers to the configured upstream `api_base`. This vulnerability can be exploited by low-privileged authenticated users in basic-auth deployments or by unauthenticated users in default deployments without `basic-auth`. The impact includes potential leakage of sensitive credentials such as cloud artifact credentials (`AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY`), which could lead to artifact poisoning and cross-boundary code execution in downstream environments. The issue is fixed in version 3.11.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Insertion of Sensitive Information Into Sent Data
The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.
How developers prevent this class of flaw
- Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.
- Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.
- Setup default error messages so that unexpected errors do not disclose sensitive information.
More Insertion of Sensitive Information Into Sent Data vulnerabilities (CWE-201)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Technical write-ups (may include proof of concept)
- huntr.com/bounties/f8e591a0-0f19-4910-b82e-16c9956f2233Exploit, Third Party Advisory
Other references
Other vulnerabilities in mlflow/mlflow
- 8.1 High severity
- 9.0 Critical severity
- 9.6 Critical severity
- 7.8 High severity
- 8.6 High severity
- 7.5 High severity
Recent Insertion of Sensitive Information Into Sent Data vulnerabilities
- 7.5 High severity
- 7.3 High severity
- 7.7 High severity
- 8.8 High severity
- 9.9 Critical severity
- 9.1 Critical severity
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