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Actively exploited

CVE-2016-6415 Cisco IOS, IOS XR, and IOS XE IKEv1 Information Disclosure Vulnerability

Cisco IOS, IOS XR, and IOS XE contain insufficient condition checks in the part of the code that handles Internet Key Exchange version 1 (IKEv1) security negotiation requests. contains an information disclosure vulnerability in the Internet Key Exchange version 1 (IKEv1) that could allow an attacker to retrieve memory contents. Successful exploitation could allow the attacker to retrieve memory contents, which can lead to information disclosure.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 19 May 2023.
  • Rated High severity (CVSS 7.5, scored by CISA).
  • It has been in the catalogue for 1,267 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

The server IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.6, IOS XE through 3.18S, IOS XR 4.3.x and 5.0.x through 5.2.x, and PIX before 7.0 allows remote attackers to obtain sensitive information from device memory via a Security Association (SA) negotiation request, aka Bug IDs CSCvb29204 and CSCvb36055 or BENIGNCERTAIN.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Cisco IOS, IOS XR, and IOS XE. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 9 Jun 2023 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2016-6415
  3. CVE record: CVE-2016-6415
  4. FIRST EPSS
  5. sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160916-ikev1
  6. securitytracker.com/id/1036841
  7. tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160916-ikev1
  8. securityfocus.com/bid/93003