Security readout for executives and security teams
Plain-English summary
This flaw affects some Cisco carrier-grade routers and could let a highly privileged local attacker run unsigned code during device boot. It is not a remote unauthenticated internet bug, but compromise could undermine router trust and confidentiality, integrity, and availability.
Executive priority
Treat as a targeted infrastructure risk. Prioritize environments where affected routers carry critical traffic or where privileged administrative access is broadly shared.
Technical view
CVE-2021-1244 is an image verification weakness in Cisco IOS XR for Cisco 8000 Series routers and NCS 540 routers running NCS540L images. Cisco describes authenticated local code execution during boot. CVSS 3.1 is 6.7 with high privileges required and high impact.
Likely exposure
Exposure is likely limited to organizations operating Cisco 8000 Series routers or NCS 540 routers with Cisco IOS XR NCS540L images. The source bundle does not provide affected version ranges.
Exploitation context
The provided sources do not show active exploitation, and the CVE is not listed as KEV. Exploitation requires authenticated local access with high privileges, reducing likelihood but increasing concern where router administration is poorly controlled.
Researcher notes
Evidence points to CWE-347, improper verification of cryptographic signatures. The bundle confirms impact and affected product families but does not include fixed versions, proof-of-concept status, or detailed exploit prerequisites beyond authenticated local high privilege.
Mitigation direction
- Inventory Cisco 8000 and NCS 540 routers in production.
- Identify NCS 540 devices running IOS XR NCS540L images.
- Check Cisco's advisory for affected releases and fixed software guidance.
- Restrict privileged local administrative access to trusted operators only.
- Apply vendor-approved IOS XR updates after confirming applicability.
Validation and detection
- Compare device model and image type against Cisco's advisory.
- Verify whether NCS 540 devices run NCS540L software images.
- Review administrative access logs for unexpected privileged local activity.
- Confirm boot image provenance and vendor-supported software state.
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-347: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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-2021-1244 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
- 6.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/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:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H0.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.7MediumVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20210203 Cisco IOS XR Software for Cisco 8000 Series Routers and Network Convergence System 540 Series Routers Image Verification 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.
Improper Verification of Cryptographic Signature
Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.