dbcve.org
Ios XeOperating system · Cisco

CVE-2024-20455

HIGH · 8.6 CVSS v3.1 Published 2024-09-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
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
A vulnerability in the process that classifies traffic that is going to the Unified Threat Defense (UTD) component of Cisco IOS XE Software in controller mode could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because UTD improperly handles certain packets as those packets egress an SD-WAN IPsec tunnel. An attacker could exploit this vulnerability by sending crafted traffic through an SD-WAN IPsec tunnel that is configured on an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: SD-WAN tunnels that are configured with Generic Routing Encapsulation (GRE) are not affected by this vulnerability.

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 · moderate confidence

A vulnerability in Cisco IOS XE Software's Unified Threat Defense (UTD) component allows an unauthenticated remote attacker to cause device reloads by sending crafted packets through SD-WAN IPsec tunnels. The UTD improperly handles certain egress packets from these tunnels, leading to denial of service. GRE-tunneled SD-WAN configurations are not affected.

MitigationApply Cisco IOS XE software updates when available; alternatively, disable UTD processing for SD-WAN IPsec tunnel traffic or migrate to GRE-encapsulated tunnels as a workaround.

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
Ios XeOperating system
Affected:= 17.1.1= 17.1.1a= 17.1.1s= 17.1.1t= 17.1.3= 17.2.1= 17.2.1a= 17.2.1r= 17.2.1v= 17.2.2= 17.2.3= 17.3.1
Ios Xe Sd WanOperating system
Affected:= 17.5.1a= 17.6.1a= 17.6.2= 17.6.4= 17.7.1a= 17.8.1a= 17.9.1a= 17.9.2a= 17.9.3a= 17.9.4= 17.10.1a= 17.11.1a

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
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 the Cisco IOS XE version
    Run 'show version' and look for the IOS XE release number in the output. Compare it to the affected version list: 17.1.1 through 17.3.1 for IOS XE, or 17.5.1a through 17.11.1a for IOS XE SD-WAN.
    Affected if The device runs any version matching the specific versions listed in the affected products.
  2. Verify UTD is enabled
    Run 'show utd status' or 'show running-config | include utd' to determine if Unified Threat Defense is configured on the device.
    Affected if UTD is actively enabled or configured on the device.
  3. Confirm SD-WAN IPsec tunnel configuration
    Run 'show sdwan tunnel' or 'show ipsec tunnel' to identify active SD-WAN tunnels. Then determine if they use IPsec encapsulation by examining the tunnel configuration with 'show running-config | include crypto ipsec'.
    Affected if The device has SD-WAN tunnels using IPsec encapsulation (not GRE-tunneled).

A device is affected if it runs an IOS XE version from the affected list, has UTD enabled, and has SD-WAN IPsec tunnels configured (GRE-tunneled SD-WAN is not vulnerable).

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco IOS XE software updates when available; alternatively, disable UTD processing for SD-WAN IPsec tunnel traffic or migrate to GRE-encapsulated tunnels as a workaround.

Recommended fix Moderate confidence

IOS XE 17.2.1 or later (17.1.x train) / 17.7.x or later (17.5.x/17.6.x SD-WAN train)

  1. 1. Identify the current IOS XE version running on the device using 'show version' command
  2. 2. Confirm the device has an SD-WAN IPsec tunnel configuration (not GRE) using 'show sdwan tunnel interface' or 'show ipsec sa'
  3. 3. Plan for a maintenance window as the device will reload during upgrade
  4. 4. Backup the current device configuration using 'copy running-config startup-config' or export via controller
  5. 5. Download the fixed IOS XE release from Cisco (17.2.1 or later for 17.1.x, 17.7.x or later for 17.5.x/17.6.x)
  6. 6. Upgrade the device using 'request platform software sdwan software upgrade' or through the controller GUI
  7. 7. After upgrade, verify the device is operational and confirm new version with 'show version'
  8. 8. Verify UTD is functioning properly with 'show utd status'
Caveat Upgrading between major.minor versions may introduce behavioral changes; review Cisco release notes for your specific train before upgrading

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

Fix this in Ios Xe Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2024-20455 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
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  • No spam, self-promotion, credentials, or personal data