Security readout for executives and security teams
Plain-English summary
This flaw can let a malicious or compromised BGP peer crash the BGP process on Cisco IOS XR systems using EVPN. The business impact is network instability or outage in environments that rely on affected routers for routing services.
Executive priority
Prioritize review where Cisco IOS XR routers carry critical EVPN routing. The issue is high severity because successful exploitation can disrupt availability, but urgency depends on whether affected devices have BGP EVPN enabled and who can send updates as valid peers.
Technical view
Cisco IOS XR incorrectly processes BGP update messages containing crafted EVPN attributes. A malformed update can cause the BGP process to restart, producing a denial of service. Cisco notes BGP traffic is accepted only from explicitly configured peers, so practical reachability depends on trusted peer access or injection into an existing valid BGP connection.
Likely exposure
Exposure is most likely in service provider, data center, or enterprise networks running Cisco IOS XR with BGP EVPN configured. The provided sources do not specify affected versions, so teams must verify platform and release details against Cisco’s advisory.
Exploitation context
The bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation is remote in network terms, but constrained to a configured valid BGP peer or traffic injected into an existing valid BGP peer connection.
Researcher notes
The key exposure boundary is the BGP trust relationship. Research should focus on IOS XR EVPN deployments, configured peer paths, evidence of BGP process instability, and Cisco advisory details for affected and fixed releases. Do not assume broad internet exposure without peer-specific evidence.
Mitigation direction
- Identify IOS XR devices running BGP EVPN and compare releases against Cisco advisory.
- Apply Cisco-recommended fixed software or mitigations if the advisory identifies them.
- Restrict BGP peering to trusted, monitored neighbors and maintain strict peer definitions.
- Monitor BGP sessions for malformed-update errors, unexpected resets, or process restarts.
- Review routing change controls for untrusted or recently added EVPN peers.
Validation and detection
- Inventory IOS XR platforms and confirm whether BGP EVPN is enabled.
- List configured BGP peers permitted to exchange EVPN routes.
- Check logs for BGP process restarts around received update events.
- Confirm current software status against Cisco advisory guidance.
- Verify operational alerts cover BGP session resets and process restarts.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-399: Exact CWE lookup
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Open ATT&CK lookupCVE-2019-16020 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H3.94Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.6HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200122 Cisco IOS XR Software BGP EVPN Denial of Service VulnerabilitiesCVE reference · vendor-advisory, x_refsource_CISCO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Resource Management Errors
Resource Management Errors represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.