Security readout for executives and security teams
Plain-English summary
CVE-2021-1518 lets a logged-in low-privileged user abuse Cisco Firepower Device Manager On-Box REST API input handling to run code on the device operating system. It is not described as unauthenticated, and the bundle does not show known active exploitation.
Executive priority
Treat this as a moderate-priority firewall management-plane risk. It requires credentials, but successful exploitation could execute code on security infrastructure, so confirm exposure and patch status promptly.
Technical view
The issue is insufficient sanitization in specific FDM On-Box REST API commands, classified as CWE-94. A crafted authenticated HTTP request can execute arbitrary code on the underlying OS. CVSS 3.1 is 6.3, with network access, low complexity, low privileges, and limited confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely where Cisco Firepower Threat Defense devices use affected FDM On-Box Software and low-privileged users can reach the REST API.
Exploitation context
The source bundle says exploitation requires valid low-privileged credentials. CISA KEV status is false, and no cited source in the bundle establishes active exploitation or public exploit availability.
Researcher notes
The bundle does not include affected version ranges, fixed versions, workarounds, or exploit telemetry. Avoid expanding scope beyond Cisco Firepower Threat Defense/FDM On-Box until the Cisco advisory confirms exact applicability.
Mitigation direction
- Review Cisco's advisory for affected release and fixed software guidance.
- Apply Cisco-provided updates or workarounds if the advisory lists them.
- Remove unnecessary low-privileged FDM user accounts.
- Restrict FDM management and REST API access to authorized administrators.
- Monitor Cisco guidance for any changed exploit or remediation status.
Validation and detection
- Inventory Cisco Firepower Threat Defense devices using FDM On-Box Software.
- Compare installed software versions against Cisco's advisory.
- Review FDM accounts for unnecessary low-privileged access.
- Check whether REST API access is limited to trusted management paths.
- Review logs for unexpected authenticated FDM API activity.
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-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-1518 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
- 6.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
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:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L2.83.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- 20210721 Cisco Firepower Device Manager On-Box Software Remote Code Execution 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 Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.