Security readout for executives and security teams
Plain-English summary
CVE-2021-1455 is a set of cross-site scripting flaws in Cisco Firepower Management Center's web management interface. An attacker would need to convince an FMC user to click a crafted link. If successful, script could run in that user's browser session and may expose browser-based sensitive information.
Executive priority
Treat this as a timely hygiene issue for security management infrastructure. It is not confirmed exploited in the provided evidence, but compromise of an administrator's FMC browser session could affect sensitive security operations.
Technical view
Cisco describes insufficient validation of user-supplied input in the FMC web-based management interface. The issue is CWE-79 XSS and is remotely reachable without authentication, but exploitation depends on user interaction. The provided bundle does not include CVSS, affected version ranges, or specific fixed releases.
Likely exposure
Organizations running Cisco Firepower Management Center are potentially exposed, especially where administrators access FMC through browsers and may receive external links. The source bundle does not specify affected versions, so exposure requires checking the Cisco advisory against deployed FMC releases.
Exploitation context
No active exploitation is supported by the provided sources, and the CVE is not marked KEV. The known attack pattern is social engineering: persuading an FMC interface user to click a crafted link, leading to script execution in that interface context.
Researcher notes
The bundle supports CWE-79 XSS in Cisco FMC with unauthenticated remote reachability and required user interaction. It does not provide CVSS, vulnerable version ranges, proof-of-concept status, exploit telemetry, or named fixed releases. Avoid assuming internet exposure or exploitation without environment evidence.
Mitigation direction
- Review Cisco's advisory for affected and fixed FMC releases.
- Apply Cisco-recommended updates or mitigations where applicable.
- Restrict FMC management access to trusted admin networks or VPN.
- Train FMC administrators to avoid unsolicited FMC-related links.
- Monitor vendor guidance for any later exploit or patch updates.
Validation and detection
- Inventory all Cisco Firepower Management Center deployments.
- Compare installed FMC versions against Cisco's advisory.
- Confirm FMC management interfaces are not publicly exposed.
- Review access paths for VPN, allowlisting, and admin-only controls.
- Check for suspicious FMC-related links reported to administrators.
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-2021-1455 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
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.