dbcve.org
Ios XeOperating system · Cisco

CVE-2022-20679

HIGH · 7.7 CVSS v3.1 Published 2022-04-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
83/100
Remediation priority · High
Remotely reachable 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 IPSec decryption routine of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to buffer exhaustion that occurs while traffic on a configured IPsec tunnel is being processed. An attacker could exploit this vulnerability by sending traffic to an affected device that has a maximum transmission unit (MTU) of 1800 bytes or greater. A successful exploit could allow the attacker to cause the device to reload. To exploit this vulnerability, the attacker may need access to the trusted network where the affected device is in order to send specific packets to be processed by the device. All network devices between the attacker and the affected device must support an MTU of 1800 bytes or greater. This access requirement could limit the possibility of a successful exploit.

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 buffer exhaustion vulnerability in the IPSec decryption routine of Cisco IOS XE Software occurs when processing traffic on configured IPsec tunnels with MTU of 1800 bytes or greater, causing the affected device to reload and result in denial of service.

MitigationApply Cisco IOS XE software updates when available; meanwhile, filter or block malicious packets targeting IPsec tunnels or reduce MTU below 1800 bytes on the path.

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:= 3.15.1xbs= 3.15.2xbs= 16.8.1= 16.8.1a= 16.8.1b= 16.8.1c= 16.8.1d= 16.8.1e= 16.8.1s= 16.8.2= 16.8.3= 16.9.1

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
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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 Cisco IOS XE version
    Run 'show version' on the device CLI and locate the IOS XE version string in the output (typically in the line beginning with 'Cisco IOS XE Software' or similar)
    Affected if The installed version matches any of these: 3.15.1xbs, 3.15.2xbs, 16.8.1, 16.8.1a, 16.8.1b, 16.8.1c, 16.8.1d, 16.8.1e, 16.8.1s, 16.8.2, 16.8.3, or 16.9.1
  2. Verify IPSec tunnel configuration
    Run 'show crypto ipsec sa' or 'show crypto ipsec profile' to check for active IPsec security associations or profiles
    Affected if Any IPsec tunnel (site-to-site or remote access) is configured and active on the device
  3. Check tunnel interface MTU values
    Run 'show interface <tunnel_interface>' for each tunnel interface listed in the IPsec configuration, or use 'show ip interface brief' and note the MTU column
    Affected if Any tunnel interface has an MTU value of 1800 bytes or greater (look for 'MTU' value in the interface output)
  4. Confirm crypto map application to interfaces
    Run 'show crypto map' to see which interfaces have crypto maps applied, then check the MTU on those physical or tunnel interfaces
    Affected if Crypto maps are applied to interfaces that have MTU set to 1800 bytes or higher

The device is affected if it runs any of the listed vulnerable IOS XE versions AND has an IPsec tunnel configured with an MTU of 1800 bytes or greater on the relevant interface.

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

Apply Cisco IOS XE software updates when available; meanwhile, filter or block malicious packets targeting IPsec tunnels or reduce MTU below 1800 bytes on the path.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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Scan for this in your stack

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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-2022-20679 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
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