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852 303 FirmwareOperating system · Wago

CVE-2019-12549

CRITICAL · 9.8 CVSS v3.0 Published 2019-06-17
Fix available
A fix is available. Upgrade to 1.1.5.s0 / 1.1.6.s0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
WAGO 852-303 before FW06, 852-1305 before FW06, and 852-1505 before FW03 devices contain hardcoded private keys for the SSH daemon. The fingerprint of the SSH host key from the corresponding SSH daemon matches the embedded private key.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

WAGO 852-303, 852-1305, and 852-1505 industrial controllers contain hardcoded SSH private keys embedded in firmware. Since the SSH host key fingerprint matches these embedded keys, an attacker who obtains the public key can deduce the corresponding private key, enabling server impersonation and man-in-the-middle attacks.

MitigationUpgrade firmware to FW06 (852-303, 852-1305) or FW03 (852-1505); if immediate patching is impossible, disable SSH access and isolate devices behind firewalls to reduce attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
852 303 FirmwareOperating system
Affected:< 1.2.2.s0
852 1305 FirmwareOperating system
Affected:< 1.1.6.s0
852 1505 FirmwareOperating system
Affected:< 1.1.5.s0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify WAGO controller model
    Determine if the device is a WAGO 852-303, 852-1305, or 852-1505 industrial controller by checking the device label, web interface, or system information
    Affected if Device is not one of these three models - vulnerability does not apply
  2. Check installed firmware version
    Access the device web interface, CLI, or use the WAGO management tool to retrieve the firmware version. Compare against: 852-303 < 1.2.2.s0, 852-1305 < 1.1.6.s0, 852-1505 < 1.1.5.s0
    Affected if Firmware version is lower than the affected threshold for your model
  3. Verify SSH service status
    Check if SSH is enabled and running on the device via the web interface under Services > SSH, or by attempting an SSH connection to the device
    Affected if SSH is disabled - the vulnerability cannot be exploited; however, SSH is typically required for normal operation
  4. Inspect for embedded SSH host keys
    If you have access to the firmware image or device filesystem, examine /etc/ssh/ or equivalent for SSH host keys. Compare fingerprints against known public keys or check for duplicate/reused keys across multiple devices
    Affected if SSH host keys match known hardcoded values from firmware or are identical across multiple devices - confirms active exploitation risk

User is affected if they run an affected firmware version (852-303 < 1.2.2.s0, 852-1305 < 1.1.6.s0, or 852-1505 < 1.1.5.s0) on these WAGO controllers with SSH enabled, as the hardcoded private keys enable MITM attacks.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.1.5.s0 / 1.1.6.s0 / 1.2.2.s0 or later
Fixed in 1.1.5.s01.1.6.s01.2.2.s0
Interim mitigation

Upgrade firmware to FW06 (852-303, 852-1305) or FW03 (852-1505); if immediate patching is impossible, disable SSH access and isolate devices behind firewalls to reduce attack surface.

Recommended fix Moderate confidence

852-303: firmware >= 1.2.2.s0 | 852-1305: firmware >= 1.1.6.s0 | 852-1505: firmware >= 1.1.5.s0

  1. 1. Identify the WAGO 852 controller model (852-303, 852-1305, or 852-1505) in your environment
  2. 2. Determine the current firmware version installed on the device
  3. 3. Download the fixed firmware version from the official WAGO support portal at www.wago.com or via cert.vde.com/ics-cert.us-cert.gov references
  4. 4. For 852-303: upgrade to firmware 1.2.2.s0 or later
  5. 5. For 852-1305: upgrade to firmware 1.1.6.s0 or later
  6. 6. For 852-1505: upgrade to firmware 1.1.5.s0 or later
  7. 7. Follow WAGO's standard firmware update procedure (typically via web-based management interface or WAGO-I/O-CHECK tool)
  8. 8. After upgrade, verify the SSH host key has changed and regenerate new SSH host keys on the device
Caveat Review WAGO release notes for any compatibility changes between versions; ensure backup of current configuration before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in 852 303 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-12549 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data