Security readout for executives and security teams
Plain-English summary
Cisco FTD had multiple CLI command injection flaws that could let a highly privileged local user run commands as root. This is not a typical internet-facing bug, but it matters where firewall admin accounts are shared, overprivileged, or compromised.
Executive priority
Treat this as a priority for firewall administration hygiene and patch verification, not as an emergency internet-wide exposure. Confirm affected FTD assets, validate upgrade status, and tighten privileged access controls.
Technical view
CVE-2021-34755 covers multiple Cisco Firepower Threat Defense Software CLI command injection vulnerabilities tied to improper input validation. The CVSS 3.1 vector is AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, meaning exploitation requires local access and high privileges but can fully affect confidentiality, integrity, and availability.
Likely exposure
Exposure is likely limited to Cisco Firepower Threat Defense deployments where an attacker already has local authenticated CLI access with high privileges. The supplied bundle does not enumerate affected or fixed versions.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Practical risk rises if administrator credentials are compromised, shared, weakly monitored, or available through jump hosts and management networks.
Researcher notes
Evidence supports local authenticated command injection with root-level impact, but version granularity and fixed-release details are not present in the supplied bundle. Avoid assuming remote exploitability or active exploitation without additional sourced evidence.
Mitigation direction
- Review Cisco's advisory for affected and fixed FTD releases.
- Upgrade or patch according to Cisco's published guidance.
- Restrict CLI access to trusted administrators only.
- Enforce least privilege and named administrator accounts.
- Monitor privileged CLI activity on FTD devices.
Validation and detection
- Inventory all Cisco Firepower Threat Defense appliances and virtual deployments.
- Compare installed FTD versions against Cisco's advisory.
- Review who has local or CLI administrative access.
- Check recent privileged CLI activity for unusual administrative behavior.
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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CWE-20: Exact CWE lookup
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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-2021-34755 mapping review
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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
- 20211027 Cisco Firepower Threat Defense Software Command Injection 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 Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.