dbcve.org
Ios XrOperating system · Cisco

CVE-2022-20849

MEDIUM · 6.1 CVSS v3.1 Published 2024-11-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
66/100
Remediation priority · Elevated
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 Broadband Network Gateway PPP over Ethernet (PPPoE) feature of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the PPPoE process to continually crash. This vulnerability exists because the PPPoE feature does not properly handle an error condition within a specific crafted packet sequence. An attacker could exploit this vulnerability by sending a sequence of specific PPPoE packets from controlled customer premises equipment (CPE). A successful exploit could allow the attacker to cause the PPPoE process to continually restart, resulting in a denial of service condition (DoS).Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.This advisory is part of the September 2022 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see .

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 XR Software's Broadband Network Gateway PPPoE feature allows an unauthenticated, adjacent attacker to cause the PPPoE process to continuously crash by sending a specific crafted packet sequence. The flaw stems from improper error handling within the PPPoE feature when processing certain packets, resulting in repeated process restarts and denial of service.

MitigationApply the Cisco software updates released in the September 2022 IOS XR Security Advisory Bundled Publication; no workarounds are available.

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 XrOperating system
Affected:= 6.5.1= 6.5.2= 6.5.3= 6.5.15= 6.6.1= 6.6.2= 6.6.3= 6.6.4= 6.6.25= 6.7.1= 6.7.2= 6.7.3

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
Adjacent
Complexity
High
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:H/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 device OS and version
    Execute 'show version' or 'admin show version' on the device to confirm it is running Cisco IOS XR and to obtain the exact software version number
    Affected if The device runs Cisco IOS XR and the version matches one of the following: 6.5.1, 6.5.2, 6.5.3, 6.5.15, 6.6.1, 6.6.2, 6.6.3, 6.6.4, 6.6.25, 6.7.1, 6.7.2, or 6.7.3
  2. Confirm PPPoE configuration on BNG
    Run 'show running-config | include pppoe' or 'show pppoe interfaces' to check if PPPoE is enabled on any interface
    Affected if PPPoE is configured and active on the device
  3. Check for PPPoE process crashes
    Review logs with 'show logging | include pppoe' or check 'show process crash' for the pppoe process to identify any recent restarts or crashes
    Affected if The PPPoE process has crashed or restarted repeatedly, indicating potential exploitation

A user is affected if the device runs a vulnerable IOS XR version (6.5.1 through 6.7.3) AND has PPPoE configured, with the vulnerability potentially indicated by PPPoE process instability.

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 the Cisco software updates released in the September 2022 IOS XR Security Advisory Bundled Publication; no workarounds are available.

Recommended fix Moderate confidence

Contact Cisco for specific fixed release (refer to September 2022 IOS XR Security Advisory)

  1. Contact Cisco technical support or visit sec.cloudapps.cisco.com to obtain the specific fixed release for IOS XR version 6.5.x
  2. Request the PPPoE security update from Cisco's IOS XR Software Security Advisory Bundled Publication (September 2022)
  3. Plan maintenance window for upgrade as PPPoE service will be briefly interrupted during the software update process
  4. After upgrade, verify PPPoE process stability using 'show process pppoe' or similar diagnostic commands
  5. Monitor system logs for any PPPoE process crashes following the upgrade
Caveat Standard IOS XR upgrade considerations apply - verify hardware compatibility and review release notes before upgrading

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

Fix this in Ios Xr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2022-20849 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