Security readout for executives and security teams
Plain-English summary
CVE-2021-1128 is an information disclosure flaw in Cisco IOS XR Software. A logged-in local user could see sensitive configuration information beyond their assigned privileges. This is not a remote takeover issue, but it matters on routers where configuration data may expose network design, credentials, or security controls.
Executive priority
Treat this as a moderate-priority network infrastructure confidentiality issue. It is most urgent where many administrators, contractors, or operational accounts have CLI access to IOS XR devices containing sensitive routing or security configuration.
Technical view
Cisco describes insufficient restriction enforcement in the IOS XR CLI parser during a specific command. The issue requires local authenticated CLI access and low privileges. Successful exploitation impacts confidentiality only, with CVSS 3.1 score 5.5 and CWE-201 classification.
Likely exposure
Exposure is limited to organizations running Cisco IOS XR Software where lower-privileged authenticated users have CLI access. The provided bundle does not include affected version ranges, CPEs, or fixed release details, so asset owners must verify against Cisco guidance.
Exploitation context
The bundle does not show CISA KEV listing or other cited evidence of active exploitation. Exploitation requires authenticated local access and use of a specific CLI command, so insider misuse or compromised admin-adjacent accounts are the main concern.
Researcher notes
Key constraints are local attack vector, low privileges, no user interaction, unchanged scope, high confidentiality impact, and no integrity or availability impact. Public bundle evidence is incomplete for affected versions and fixes, so avoid broader product claims.
Mitigation direction
- Review Cisco advisory for affected releases and fixed software guidance.
- Limit IOS XR CLI access to trusted administrative accounts.
- Audit least-privilege role assignments for local authenticated users.
- Prioritize remediation on devices holding sensitive network configuration.
- Monitor Cisco guidance for version-specific fixes or workarounds.
Validation and detection
- Inventory Cisco IOS XR devices and software versions.
- Compare deployed versions against the Cisco advisory.
- Review accounts with local CLI access and low-privilege roles.
- Check whether sensitive configuration data is accessible to unintended users.
- Confirm remediation status after applying Cisco-recommended updates.
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-201: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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-2021-1128 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
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N1.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20210203 Cisco IOS XR Software Unauthorized Information Disclosure 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.
Insertion of Sensitive Information Into Sent Data
Insertion of Sensitive Information Into Sent Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.