CVE-2026-64849: MLflow tracking server unauthenticated full-read SSRF via webhook test

Exploited in the wild Critical 9.3 EPSS 10.0%

On a default MLflow tracking server (no auth plugin) the webhooks API is unauthenticated, and POST /api/2.0/mlflow/webhooks/{id}/test returns the upstream response. The SSRF guard checks only the original URL, while delivery follows redirects and re-resolves DNS, so an attacker can reach cloud metadata (e.g. AWS IMDS credentials) and internal services and read the replies. Fixed in MLflow 3.15.0 with connection-time IP validation; CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-19.

CVE-2026-64849CVE identifier
9.3CVSS 3.1 base score (critical)
2026-08-19added to CISA's exploited list (US federal deadline 2026-09-02)
10.0%EPSS: chance of exploitation in the next 30 days (higher than 96% of CVEs)
2026-08-17published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run the affected software and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
Restart the MLflow tracking server process.
Because this flaw is being exploited, also check the server for signs of compromise.

Affected and fixed versions

Affected:

MLflow 3.3.0 before 3.15.0 per the CVE record (the GitHub advisory lists >= 3.10.0, < 3.15.0)

Fixed in:

MLflow 3.15.0

Am I affected?

pip show mlflow | grep -i ^version

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Built from source

pip install --upgrade 'mlflow>=3.15.0'
# restart 'mlflow server'

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

Look for signs of exploitation

Tracking-server access logs: POST /api/2.0/mlflow/webhooks (webhook creation) followed by POST /api/2.0/mlflow/webhooks/<id>/test from unexpected clients; outbound requests from the server to 169.254.169.254 or loopback addresses.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

https://github.com/mlflow/mlflow/pull/24258 ; https://github.com/mlflow/mlflow/issues/24179 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-64849

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC and reviewed by an editor. Always confirm with your vendor's advisory.