Security readout for executives and security teams
Plain-English summary
This Cisco IOS XR issue can let someone reach the NETCONF management service over SSH even when an ACL was meant to block it. It does not affect the device’s default SSH process. The attacker still needs valid credentials, so the main business risk is weakened management-plane access control on routers running affected IOS XR Software.
Executive priority
Treat this as a management-plane control weakness, not a broad unauthenticated takeover. Prioritize review where IOS XR routers expose NETCONF over SSH or rely on ACLs for management isolation, especially on critical network infrastructure.
Technical view
The vulnerability is an ACL bypass in NETCONF over SSH access-control logic in Cisco IOS XR Software, caused by a missing ACL check. A successful connection can reach the NETCONF port despite a deny rule. The source lists CWE-284 and CVSS 3.0 score 5.3. Valid credentials are required for device access.
Likely exposure
Exposure is most likely on Cisco IOS XR devices where NETCONF over SSH is enabled and ACLs are used to restrict that management service. The provided sources do not identify exact affected versions, CPEs, or deployment prevalence.
Exploitation context
The source bundle does not show CISA KEV listing or any cited evidence of active exploitation. Exploitation requires network reachability to NETCONF over SSH and valid credentials, but the ACL meant to deny that path may not be enforced.
Researcher notes
Key evidence is limited to the CVE record and Cisco advisory reference. The source bundle says credentials are required, although the CVSS vector lists PR:N. Do not assume affected versions, exploit availability, or fixed releases beyond Cisco’s advisory.
Mitigation direction
- Review Cisco’s advisory for affected IOS XR releases and official fixed-software guidance.
- Inventory IOS XR devices with NETCONF over SSH enabled.
- Do not rely on the affected NETCONF over SSH ACL as the only control.
- Limit valid management credentials to authorized administrators only.
- Monitor Cisco guidance for version-specific remediation details.
Validation and detection
- Identify IOS XR devices using NETCONF over SSH.
- Review ACLs intended to deny NETCONF over SSH access.
- Confirm whether valid credentials exist for exposed management users.
- Check management access logs for unexpected NETCONF over SSH connections.
- Compare device versions against Cisco’s advisory guidance.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-284: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2019-15998 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
- Medium
- CVSS
- 5.3 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
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:U/C:N/I:L/A:N3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
5.3MediumVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20191120 Cisco IOS XR Software NETCONF Over Secure Shell ACL Bypass 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 Access Control
Improper Access Control represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.