Security readout for executives and security teams
Plain-English summary
Cisco FMC's web management interface had multiple cross-site scripting flaws. An attacker would need to convince an FMC interface user to open a crafted link, then script could run in that user's browser session and potentially read browser-based sensitive data.
Executive priority
Treat this as a moderate-priority administrative-interface risk. It is not described as actively exploited, but FMC is security infrastructure, so confirm versions and apply Cisco's guidance during the next appropriate maintenance window.
Technical view
CVE-2021-1456 is a CWE-79 issue in Cisco Firepower Management Center caused by insufficient validation of user-supplied input in the web UI. CVSS 3.1 score is 4.8, with required user interaction and changed scope, affecting confidentiality and integrity at low impact.
Likely exposure
Exposure is limited to organizations running Cisco Firepower Management Center where users can access the management interface. The bundle does not provide affected version ranges, so teams must confirm installed FMC versions against Cisco guidance.
Exploitation context
The sources describe link-based XSS requiring a user of the FMC interface to click a crafted link. The bundle does not indicate known active exploitation, and CISA KEV status is false.
Researcher notes
The record identifies XSS in the FMC web UI with UI-dependent exploitation and low confidentiality/integrity impact. Version and remediation specifics are not present in the supplied bundle; rely on the Cisco advisory for product-specific validation.
Mitigation direction
- Check Cisco's advisory for affected and fixed FMC releases.
- Upgrade Cisco FMC according to vendor guidance.
- Restrict access to the FMC management interface to trusted networks.
- Warn FMC administrators not to open unexpected management-interface links.
Validation and detection
- Inventory Cisco Firepower Management Center deployments and versions.
- Compare installed versions with Cisco's advisory.
- Confirm management UI exposure is limited to authorized networks.
- Review browser or proxy logs for suspicious FMC interface link 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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2021-1456 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
- 4.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/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:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N1.72.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.8MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20210428 Cisco Firepower Management Center Software Cross-Site Scripting 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 Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.