Ios XrOperating system · Cisco
CVE-2022-20758
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 · uneditedA vulnerability in the implementation of the Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to the incorrect processing of a BGP update message that contains specific EVPN attributes. An attacker could exploit this vulnerability by sending a BGP update message that contains specific EVPN attributes. To exploit this vulnerability, an attacker must control a BGP speaker that has an established trusted peer connection to an affected device that is configured with the address family L2VPN EVPN to receive and process the update message. This vulnerability cannot be exploited by any data that is initiated by clients on the Layer 2 network or by peers that are not configured to accept the L2VPN EVPN address family. A successful exploit could allow the attacker to cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP updates only from explicitly defined peers. For this vulnerability to be exploited, the malicious BGP update message must either come from a configured, valid BGP peer or be injected by the attacker into the affected BGP network on an existing, valid TCP connection to a BGP peer.
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 confidenceA vulnerability in Cisco IOS XR Software's BGP EVPN implementation allows an unauthenticated, remote attacker to cause denial of service by sending specially crafted BGP update messages containing specific EVPN attributes. Successful exploitation causes the BGP process to restart unexpectedly. The attacker must control a BGP speaker with an established trusted peer connection to a device configured with L2VPN EVPN address family.
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
< 6.8.2>= 7.0, < 7.3.2>= 7.4, < 7.4.2CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/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 checksWork through these to decide whether this CVE applies to you.
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Verify Cisco IOS XR versionRun 'show version' or check the system banner to identify the installed IOS XR versionAffected if The version falls below 6.8.2, between 7.0.0 and 7.3.2, or between 7.4.0 and 7.4.2 (the version is in the affected ranges)
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Confirm BGP is configuredRun 'show bgp all' or 'show running-config | include router bgp' to verify BGP is enabledAffected if BGP is actively configured and running on the device
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Check for L2VPN EVPN address familyRun 'show running-config | section router bgp' and look for 'address-family l2vpn evpn' under the BGP configurationAffected if The L2VPN EVPN address family is configured under BGP, enabling EVPN capability
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Identify BGP peer relationshipsRun 'show bgp all neighbors' to list all BGP peers and their statusAffected if There are established BGP peer connections, particularly to untrusted or externally accessible peers
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Check for recent BGP process restartsRun 'show log' or 'show process bgp' to look for unexpected BGP process restarts or crashesAffected if BGP process has restarted unexpectedly or shows crash information in system logs
The device is affected if it runs a vulnerable IOS XR version AND has BGP with L2VPN EVPN address family configured AND has BGP peer connections to untrusted sources.
Generated from the published advisory. Verify against your own configuration.
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 · scoped6.8.27.3.27.4.2
Apply Cisco IOS XR security updates when available. Until then, strictly limit BGP peer relationships to trusted sources, monitor for unexpected BGP process restarts, and consider additional BGP MD5 authentication and route filtering to reduce exposure.
6.8.2 or later (6.x branch); 7.3.2 or later (7.0-7.3.x branch); 7.4.2 or later (7.4.x branch)
- 1. Identify the current Cisco IOS XR version by running 'show version' on the affected device
- 2. Determine which upgrade path applies based on current version (6.x branch, 7.0-7.3.x branch, or 7.4.x branch)
- 3. Download the appropriate fixed software version from Cisco (6.8.2 or later for 6.x, 7.3.2 or later for 7.0-7.3.x, 7.4.2 or later for 7.4.x)
- 4. Schedule a maintenance window as the BGP process restart will cause network disruption
- 5. Back up the current device configuration using 'admin commit' and 'show running-config'
- 6. Install the fixed IOS XR version following Cisco's standard upgrade procedure
- 7. Verify the upgrade completed successfully and BGP peers re-established using 'show bgp session' and 'show bgp l2vpn evpn summary'
- 8. Confirm the BGP process is stable and not crashing using 'show process bgp'
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Ios Xr
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-20758 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2022-20758 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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