Security readout for executives and security teams
Plain-English summary
This issue can let a low-privileged authenticated user disrupt IS-IS routing on Cisco IOS XR devices by abusing SNMP handling. The business risk is network instability or outage on infrastructure that depends on affected routers. The source bundle does not identify active exploitation.
Executive priority
Treat as high priority for core or service-provider routing environments. It is not a data-theft issue, but disruption of IS-IS can affect routing availability and business connectivity. Urgency depends on whether SNMP access is tightly controlled and whether affected IOS XR versions are present.
Technical view
CVE-2019-16027 is a Cisco IOS XR IS-IS process denial-of-service flaw caused by improper handling of SNMP requests for specific OIDs. It is network-reachable, low complexity, requires privileges, needs no user interaction, and affects availability only. CVSS v3.0 is 7.7 High.
Likely exposure
Likely exposure is Cisco IOS XR devices running IS-IS where SNMP is enabled and reachable by authenticated users. The provided source bundle lists affected versions as unspecified, so teams must confirm applicability through Cisco’s advisory and their installed IOS XR releases.
Exploitation context
The sources describe an authenticated remote attacker sending a crafted SNMP request to trigger a DoS in the IS-IS process. KEV status is false, and the bundle provides no cited evidence of public exploitation or weaponized use.
Researcher notes
Evidence is limited to the CVE record and Cisco advisory reference. The affected version range is not included in the supplied bundle. Analysis should focus on IOS XR, IS-IS enabled devices, SNMP exposure, privilege requirements, and availability impact without assuming broader Cisco product impact.
Mitigation direction
- Check Cisco’s advisory for affected releases, fixed software, and supported workarounds.
- Prioritize remediation for IOS XR routers running IS-IS in production networks.
- Limit SNMP access to trusted management systems and approved users.
- Review SNMP authentication and authorization for least-privilege access.
- Monitor routing stability and IS-IS process health until remediation is complete.
Validation and detection
- Inventory Cisco IOS XR devices and identify those running IS-IS.
- Confirm whether SNMP is enabled and reachable on those devices.
- Compare installed IOS XR releases against Cisco’s advisory guidance.
- Review logs for IS-IS process restarts or instability around SNMP activity.
- Document any uncertainty where affected version data is unavailable.
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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Open ATT&CK lookupCVE-2019-16027 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.7 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:L/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:L/UI:N/S:C/C:N/I:N/A:H3.14Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.7HighVector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200122 Cisco IOS XR Software Intermediate System–to–Intermediate System Denial of Service VulnerabilityCVE 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.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.