● High · CVSS 8.6

How to Fix CVE-2026-2652: Authentication Bypass in mlflow/mlflow

Q: Is CVE-2026-2652 being exploited in the wild?

Public exploitation has not been confirmed by CISA at the time of writing. Treat the patch as time-sensitive anyway; reports often lag actual abuse.

Q: Will a WAF or IDS rule fully mitigate CVE-2026-2652?

No. Network-layer filters can reduce noise and slow opportunistic scanners, but they will not stop a determined attacker. The vendor patch is the only durable fix.

Q: Do I need to assume compromise if my mlflow/mlflow was internet-facing and unpatched?

For an unauthenticated RCE-class flaw exposed to the public internet during the known exploitation window, yes. Review logs, rotate credentials the process could access, and look for unexpected accounts, scheduled tasks, or outbound connections.

Other vulnerabilities in the same area that are worth patching alongside this one:

How to Fix CVE-2026-8734: SQL Injection in Pamirs — SQL Injection in Pamirs
How to Fix CVE-2026-26334: Hard-coded Credentials in VeraSMART — Hard-coded Credentials in VeraSMART
How to Fix CVE-2026-0875: Command Injection in Shared Components , Command Injection in Shared Components
How to Fix CVE-2026-27507: Hardcoded credentials in 10G08-0800GSM Network Switch , Hardcoded credentials in 10G08-0800GSM Network Switch
How to Fix CVE-2026-2627: Critical Vulnerability in FBackup , Critical Vulnerability in FBackup

*By Sai Kiran Pandrala*

⚡ At a glance


Severity	CVSS 8.6 - High
Actively exploited?	Not currently listed in CISA KEV
Affected	unspecified < 3.10.0
Fixed in	version
Type (CWE)	CWE-305: Authentication Bypass by Primary Weakness

What is CVE-2026-2652?

CVE-2026-2652 is an authentication bypass in mlflow/mlflow. A flaw in the authentication or session-handling logic lets a remote attacker reach administrative functions without valid credentials. In several reported cases this leads directly to remote code execution. Vendor 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.

Why this CVE matters

Authentication bypass on a network appliance or admin console is a top-tier target. Once the attacker is past the login, every administrative endpoint becomes available, including the ones that change settings, upload firmware, or run shell commands.

For deployments of mlflow/mlflow that have been exposed to the public internet during the disclosure window, the operating assumption should be that scanning has already happened. Even where exploitation has not been publicly observed, scanning for the vulnerable fingerprint is cheap and routine. Patching closes the door; log review and credential rotation close out the rest of the response.

Am I affected?

You are affected if your installation matches any of these version ranges:

mlflow/mlflow: unspecified < 3.10.0

Check your installed version against the list above. If you cannot determine the version, treat the system as affected and follow the upgrade path below.

Open mlflow/mlflow's About dialog or run the vendor-documented version-check command. Compare the result against the affected ranges in the advisory.

How to fix CVE-2026-2652

Read the vendor advisory in full: https://huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756
Upgrade mlflow/mlflow to the patched build listed in the vendor advisory.
Back up the configuration (and database, where applicable) before upgrading.
Rotate any credentials, API keys, or session tokens that the vulnerable service touched. An unauthenticated RCE-class flaw means anything the process could see should be treated as exposed.
Apply the patch in a maintenance window. For HA pairs, upgrade the standby node first, fail over, then upgrade the former primary.
Restart the affected service so the patched binary loads, then verify the new version (see verification section).

The commands below are runnable starting points. Adapt the package name, target version, and host paths to your environment using the vendor advisory linked under References.

npm / Yarn / pnpm


# Vendor advisory: https://huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756
# Update to the patched release named in the advisory
npm install mlflow-mlflow@latest
# or pin to the exact fixed version from the vendor advisory
npm install mlflow-mlflow@<patched-version>
npm ls mlflow-mlflow

PyPI (pip / Poetry)


# Vendor advisory: https://huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756
pip install --upgrade mlflow-mlflow
pip show mlflow-mlflow | grep -i version
# Poetry:
poetry add mlflow-mlflow@^<patched-version>

Docker / container


# Vendor advisory: https://huntr.com/bounties/5aeff5f0-49c7-4180-b5cb-c9a046f16756
docker pull <your-registry>/mlflow-mlflow:<patched-tag>
docker stop <app> && docker rm <app>
docker run -d --name <app> <your-registry>/mlflow-mlflow:<patched-tag>

PowerShell detect/upgrade/verify/log (Windows)


# CVE-2026-2652 remediation runner. Adapt version checks to your environment.
$log = "C:\Logs\CVE-2026-2652-fix.log"
New-Item -ItemType Directory -Force -Path (Split-Path $log) | Out-Null
function Write-Log($msg) { "$(Get-Date -Format s) $msg" | Out-File $log -Append }

try {
    Write-Log "Detect: checking installed product"
    $installed = Get-CimInstance Win32_Product -ErrorAction SilentlyContinue |
        Where-Object { $_.Name -match 'mlflow/mlflow' }
    if (-not $installed) { Write-Log "Product not installed; nothing to do"; return }
    Write-Log "Found version $($installed.Version)"

    Write-Log "Backup: copying program files and registry hive"
    $stamp = Get-Date -Format yyyyMMdd-HHmm
    $backup = "C:\Backup\CVE-2026-2652-$stamp"
    New-Item -ItemType Directory -Force -Path $backup | Out-Null
    Copy-Item $installed.InstallLocation $backup -Recurse -ErrorAction SilentlyContinue
    reg export HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall "$backup\uninstall.reg" /y | Out-Null

    Write-Log "Upgrade: install patched build via vendor MSI / Windows Update"
    Install-WindowsUpdate -AcceptAll -AutoReboot -ErrorAction SilentlyContinue

    Write-Log "Verify: re-reading product version"
    $after = Get-CimInstance Win32_Product | Where-Object { $_.Name -match 'mlflow/mlflow' }
    Write-Log "Post-patch version: $($after.Version)"
    if ($after.Version -ne $installed.Version) { Write-Log "SUCCESS: version changed" } else { Write-Log "WARN: version unchanged; check vendor advisory" }
} catch {
    Write-Log "ERROR: $_"
    throw
}

Bash detect/upgrade/verify/log (Linux)


#!/usr/bin/env bash
# CVE-2026-2652 remediation runner. Re-runnable, exits non-zero on failure.
set -euo pipefail
log() { printf '%s %s\n' "$(date -Is)" "$*" | tee -a /var/log/cve-2026-2652-fix.log; }

log "Detect: current mlflowmlflow version"
if command -v dpkg >/dev/null 2>&1; then
    current=$(dpkg-query -W -f='${Version}' mlflowmlflow 2>/dev/null || echo "not-installed")
elif command -v rpm >/dev/null 2>&1; then
    current=$(rpm -q --qf '%{VERSION}-%{RELEASE}' mlflowmlflow 2>/dev/null || echo "not-installed")
else
    current="unknown"
fi
log "Current: $current"

log "Backup: snapshotting config"
backup="/var/backups/cve-2026-2652-$(date +%Y%m%d-%H%M)"
mkdir -p "$backup"
[ -d /etc/mlflowmlflow ] && cp -a /etc/mlflowmlflow "$backup/" || true

log "Upgrade: applying vendor patch"
if command -v apt-get >/dev/null 2>&1; then
    sudo apt-get update -qq
    sudo apt-get install -y --only-upgrade mlflowmlflow
elif command -v dnf >/dev/null 2>&1; then
    sudo dnf upgrade -y mlflowmlflow
elif command -v yum >/dev/null 2>&1; then
    sudo yum update -y mlflowmlflow
fi

log "Verify: re-reading mlflowmlflow version"
if command -v dpkg >/dev/null 2>&1; then
    after=$(dpkg-query -W -f='${Version}' mlflowmlflow)
else
    after=$(rpm -q --qf '%{VERSION}-%{RELEASE}' mlflowmlflow)
fi
log "After: $after"

if [ "$after" != "$current" ]; then
    log "SUCCESS: mlflowmlflow upgraded"
else
    log "WARN: version unchanged. Confirm the patched build is in your repository."
    exit 1
fi

If you cannot patch immediately

Restrict access to the affected administrative interface to trusted internal networks. Disable the vulnerable component if the vendor documents that as an interim option. Patch immediately when feasible.

How to verify the fix worked

After applying the patch, verify the running version in the product's admin UI or via the vendor-documented CLI command.
Confirm the patched build matches the version listed in the vendor advisory.
Run an authenticated vulnerability scan with a current signature set and confirm the scanner no longer flags CVE-2026-2652.
Review logs for the entire pre-patch window for indicators of compromise listed in the vendor or CISA advisory.
Confirm any network-layer mitigations that were applied as a stopgap have been reverted (or left in place intentionally) once the patch is verified.

If your installation was internet-reachable during the disclosure window, treat log review as part of the remediation rather than an optional follow-up. Look for unexpected administrator accounts in mlflow/mlflow, scheduled tasks or cron jobs you did not create, new files in web-accessible directories, and outbound connections to addresses not in your baseline. Suspicious requests to the vulnerable endpoint immediately followed by successful 200-class responses with unusually large bodies are a strong indicator of exploitation.

Frequently asked questions

Is CVE-2026-2652 being exploited in the wild?