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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 24 Mar 2022.
iOSOperating system · Cisco

CVE-2017-12235

HIGH · 7.5 CVSS v3.1 Published 2017-09-29
Fix available
A fix is available. Upgrade to after 15.6 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild 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
A vulnerability in the implementation of the PROFINET Discovery and Configuration Protocol (PN-DCP) for Cisco IOS 12.2 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to the improper parsing of ingress PN-DCP Identify Request packets destined to an affected device. An attacker could exploit this vulnerability by sending a crafted PN-DCP Identify Request packet to an affected device and then continuing to send normal PN-DCP Identify Request packets to the device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to process PROFINET messages. Beginning with Cisco IOS Software Release 12.2(52)SE, PROFINET is enabled by default on all the base switch module and expansion-unit Ethernet ports. Cisco Bug IDs: CSCuz47179.

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

A vulnerability in Cisco IOS PROFINET Discovery and Configuration Protocol (PN-DCP) allows an unauthenticated remote attacker to cause device reloads. The flaw is in improper parsing of ingress PN-DCP Identify Request packets; exploitation requires sending a crafted packet followed by normal PN-DCP Identify Request packets, triggering a denial of service.

MitigationApply available Cisco IOS security updates or patches for this vulnerability. If updates are unavailable, consider disabling PROFINET on unaffected ports or implementing network segmentation to limit exposure to untrusted networks.

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
iOSOperating system
Affected:>= 12.2, <= 15.6

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 device and IOS version
    Run 'show version' on the device to obtain the Cisco IOS version number
    Affected if The IOS version falls between 12.2 and 15.6 inclusive (for example, 15.2(4)E, 15.5(3)T, etc.)
  2. Confirm PN-DCP protocol is present
    Run 'show inventory' or 'show module' to see if the device supports PROFINET capabilities; check if PN-DCP related features appear in the IOS feature set
    Affected if The device IOS image includes PROFINET/PROFINET DCP support
  3. Check for active PN-DCP configuration
    Run 'show running-config | include profinet' or 'show profinet status' (if available on the device) to see if PROFINET is configured
    Affected if PN-DCP is enabled or configured on any interface or globally on the device
  4. Identify interfaces with PROFINET settings
    Run 'show running-config' and search for 'profinet' or 'pn-dcp' keywords in the interface configurations
    Affected if Any interface has PROFINET or PN-DCP settings applied (for example, 'profinet enable' or 'profinet id' on an interface)
  5. Verify PN-DCP Identify Request processing is active
    Check if the device responds to PROFINET discovery requests; use 'show profinet statistics' or 'show profinet interface' if supported
    Affected if The device has PN-DCP processing active and would respond to Identify Request packets

The device is affected if it runs Cisco IOS versions 12.2 through 15.6, has PROFINET/PN-DCP enabled, and has PN-DCP configuration present on interfaces or globally.

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.

From vendor data
Upgrade available Upgrade to a release after 15.6
Interim mitigation

Apply available Cisco IOS security updates or patches for this vulnerability. If updates are unavailable, consider disabling PROFINET on unaffected ports or implementing network segmentation to limit exposure to untrusted networks.

Fix this in iOS Exploited in the wild — priority engagement
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  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
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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-2017-12235 in production — separate from our analysis above.

No notes yet

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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