Security readout for executives and security teams
Plain-English summary
CVE-2021-1420 lets an unauthenticated attacker alter certain Cisco Webex Meetings pages in a user’s browser if the user opens a crafted link. The main risk is misleading users, redirecting them to malicious sites, or enabling further client-side attacks. It is not described as server takeover or data theft.
Executive priority
Treat this as a moderate phishing-adjacent web risk. Prioritize confirmation of exposure and vendor-guided remediation, especially where Webex is heavily used for executive, customer, or partner meetings.
Technical view
Cisco describes improper checks on parameter values in affected Webex Meetings pages, mapped to CWE-80. Exploitation requires network access, no privileges, and user interaction. Successful exploitation can inject HTML into the affected page context, causing low integrity impact with changed scope under CVSS 3.1.
Likely exposure
Exposure is most relevant for organizations using Cisco Webex Meetings where users can be persuaded to open Webex-related links. The source bundle does not identify exact affected versions or deployment conditions.
Exploitation context
The source bundle does not report active exploitation, and KEV status is false. The attack requires social engineering: a user must follow a crafted link. Impact is client-side page modification, redirection, or possible follow-on browser-side attacks.
Researcher notes
Evidence supports HTML injection through affected parameters, not arbitrary code execution. The bundle lacks affected version ranges, patch names, and exploitation evidence, so validation should center on Cisco’s advisory and local Webex deployment details.
Mitigation direction
- Review Cisco’s advisory for affected releases and fixed software details.
- Apply Cisco-provided updates or mitigations where the advisory indicates exposure.
- Warn users to treat unsolicited Webex meeting links cautiously.
- Use email and web filtering to reduce suspicious Webex-themed link delivery.
Validation and detection
- Inventory Cisco Webex Meetings usage and versions in the environment.
- Compare deployed versions and services against Cisco’s advisory.
- Review security monitoring for suspicious Webex-themed redirects or reports.
- Confirm user-facing Webex links come from trusted organizational sources.
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-80: 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-2021-1420 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:L/PR:N/UI:R/S:C/C:N/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:N/UI:R/S:C/C:N/I:L/A:N2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.7MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20210407 Cisco Webex Meetings HTML Injection 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 Script-Related HTML Tags in a Web Page (Basic XSS)
Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.