Security Digest · Vulnerability record
CVE-2026-4035: MLflow: Environment variable injection in AI Gateway secrets enables server-side credential exfiltration
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.
CVSS 7.7 High EPSS 0.7% · p51
Should you act?
Normal patch cycle
No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.7%, percentile 51: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 51% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
mlflow(PyPI) < 3.11.0, fixed in 3.11.0. Check your lockfile, including transitive dependencies.
What it is
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 apikey field in gateway secrets can accept $ENVVAR 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 apibase. 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 (AWSACCESSKEYID, AWSSECRETACCESSKEY), which could lead to artifact poisoning and cross-boundary code execution in downstream environments. The issue is fixed in version 3.11.0.
From the GitHub advisory
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 apikey field in gateway secrets can accept $ENVVAR 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 apibase. 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 (AWSACCESSKEYID, AWSSECRETACCESSKEY), which could lead to artifact poisoning and cross-boundary code execution in downstream environments. The issue is fixed in version 3.11.0.
Weakness type: CWE-201.
Product: mlflow (PyPI) · Assigned by: @huntr_ai · Published: 2026-06-03
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | mlflow | < 3.11.0 | 3.11.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| mlflow | mlflow/mlflow | unspecified < 3.11.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| @huntr_ai | 3.0 | 9.1 Critical | CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L |
| redhat-SADP | 3.1 | 7.7 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
| GitHub | 3.1 | 9.1 | CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: low (any account)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable no, technical impact partial.
- FIRST EPSS (model of 2026-10-21): 0.66% probability of exploitation activity in the next 30 days; percentile 51.
Timeline
- — CVE record published by @huntr_ai
- — GitHub-reviewed advisory GHSA-g35p-px32-whv6 published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-g35p-px32-whv6 github.com
- CVE.org record CVE-2026-4035 cve.org
- NVD entry CVE-2026-4035 nvd.nist.gov
Other references from the CVE record and advisory
- huntr.com huntr.com
- github.com github.com
- access.redhat.com access.redhat.com
- RHBZ#2484318 bugzilla.redhat.com
- security.access.redhat.com security.access.redhat.com