Security readout for executives and security teams
Plain-English summary
This issue can make affected Cisco IOS XR routers restart their BGP process when they process specially malformed EVPN update messages. The business impact is network disruption, not data theft. Exploitation requires the message to come from a configured BGP peer or be injected into an existing valid BGP connection.
Executive priority
Treat as high priority for networks where Cisco IOS XR BGP EVPN supports critical routing. Urgency depends on whether affected devices have valid peers that could be compromised or untrusted. The source bundle does not provide fixed-version detail, so vendor guidance should drive remediation timing.
Technical view
CVE-2019-16023 covers Cisco IOS XR BGP EVPN parsing flaws caused by incorrect processing of crafted EVPN attributes in BGP update messages. Successful exploitation can unexpectedly restart the BGP process, causing denial of service. CVSS is 8.6 high, with network attack vector and high availability impact.
Likely exposure
Exposure is most likely on Cisco IOS XR deployments using BGP EVPN with configured BGP peers. Internet exposure alone is not enough if BGP peers are tightly controlled, but compromised, malicious, or reachable valid peers increase risk.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation. The attacker must be a valid configured BGP peer or inject traffic into an existing valid TCP connection to a peer.
Researcher notes
The key constraint is peer validity: Cisco IOS XR accepts BGP traffic only from explicitly defined peers. Research should focus on affected IOS XR EVPN deployments, peer trust assumptions, and operational evidence of BGP process restarts. Do not assume broad unauthenticated internet exploitability from the CVSS alone.
Mitigation direction
- Review Cisco advisory for affected and fixed IOS XR releases.
- Apply Cisco-recommended updates or mitigations for affected releases.
- Remove unnecessary BGP peers and validate peer trust boundaries.
- Monitor routers for unexpected BGP process restarts.
- Prioritize EVPN environments where routing availability is business-critical.
Validation and detection
- Inventory Cisco IOS XR devices running BGP EVPN.
- Compare IOS XR versions against Cisco advisory guidance.
- Review configured BGP peers for necessity and trust level.
- Check logs for unexpected BGP process restarts.
- Confirm monitoring alerts cover BGP session instability.
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
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ATT&CK lookup starting points
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Open ATT&CK lookupCVE-2019-16023 mapping review
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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.