Security readout for executives and security teams
Plain-English summary
Cisco WSA appliances have a management-interface XSS flaw. An attacker cannot simply break in directly; they must convince a user of the interface to upload a crafted file. If successful, malicious script could run in that user’s browser session and expose sensitive browser-based information.
Executive priority
Treat as a moderate-priority appliance management risk. It is not described as actively exploited or directly wormable, but successful exploitation could affect administrator browser sessions and sensitive management data. Prioritize faster where WSA administration is exposed beyond trusted networks.
Technical view
CVE-2021-1490 is a CWE-79 XSS issue in Cisco AsyncOS for Cisco Web Security Appliance. The flaw is improper validation of user-supplied input in the web-based management interface. The CVSS 3.1 score is 4.7 with network access, high complexity, no privileges, and required user interaction.
Likely exposure
Exposure is limited to organizations running Cisco Web Security Appliance with the affected AsyncOS management interface. The bundle does not identify exact affected versions. Risk is higher if the management interface is reachable from broad networks or if administrators handle untrusted files.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires social engineering: a remote unauthenticated attacker persuades a user to upload a crafted file to the affected device.
Researcher notes
Do not assume affected versions from this bundle; they are not enumerated here. The exploitation path depends on user interaction and file upload behavior, consistent with CVSS AC:H and UI:R. Focus validation on product/version identification, management access paths, and Cisco advisory alignment.
Mitigation direction
- Review Cisco’s advisory for affected and fixed AsyncOS releases.
- Upgrade or apply vendor-recommended fixes where applicable.
- Restrict WSA management interface access to trusted administrative networks.
- Warn administrators not to upload untrusted files to management interfaces.
- Monitor management-interface activity for unusual uploads or sessions.
Validation and detection
- Inventory Cisco WSA appliances and AsyncOS versions.
- Check whether each appliance matches Cisco’s advisory scope.
- Verify management interfaces are not broadly reachable.
- Review recent management uploads and administrator session logs.
- Confirm remediation status against Cisco guidance.
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-2021-1490 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
- 4.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/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:H/PR:N/UI:R/S:C/C:L/I:L/A:N1.62.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.7MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20210505 Cisco Web Security Appliance Cross-Site Scripting 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 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.