Security readout for executives and security teams
Plain-English summary
CVE-2021-37518 is a UXSS issue in Vimium Extension 1.66 and earlier. A remote attacker could abuse the omnibar feature after user interaction to run arbitrary code, risking browser data exposure or page manipulation. The provided sources do not show confirmed active exploitation.
Executive priority
Treat this as a moderate endpoint-browser risk. It is not KEV-listed in the provided bundle, but extensions can widen browser exposure. Prioritize inventory and update verification, especially for users handling sensitive web applications or regulated data.
Technical view
The CVE describes CWE-79 universal cross-site scripting in Vimium’s omnibar. CVSS 3.1 is 6.1: network reachable, low complexity, no privileges, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact.
Likely exposure
Exposure is likely limited to endpoints where users have Vimium Extension 1.66 or earlier installed. The source bundle does not identify specific browsers, package channels, CPEs, enterprise configurations, or affected environments beyond the extension name and version range.
Exploitation context
The vulnerability is remotely reachable but requires user interaction. KEV status is false, and the provided references do not establish active exploitation. The reported attack path is through the Vimium omnibar feature; no safe source-grounded exploit prerequisites beyond that are provided.
Researcher notes
The public bundle is sparse: affected vendor/product fields are n/a, while the title and description name Vimium Extension 1.66 and earlier. Do not infer browser-specific scope, exploit maturity, or exact fixed version without checking upstream release evidence.
Mitigation direction
- Inventory browsers for Vimium Extension installations and versions.
- Prioritize remediation for Vimium 1.66 and earlier.
- Check Vimium upstream guidance, issue 3832, and PR 3850 for fix mapping.
- Update Vimium if a fixed release is available from the trusted extension channel.
- Disable or remove affected Vimium versions where patch status cannot be confirmed.
Validation and detection
- Confirm whether Vimium is installed on managed endpoints.
- Record installed Vimium versions and flag 1.66 or earlier.
- Review browser extension management policies for unmanaged Vimium installs.
- Check vendor issue and pull request references for remediation status.
- Document any temporary disablement or exception decisions.
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 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-2021-37518 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
- 6.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/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:L/PR:N/UI:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/philc/vimium/issues/3832CVE reference
- https://github.com/philc/vimium/pull/3850CVE reference
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.