Security readout for executives and security teams
Plain-English summary
Older Elvish versions included a web UI backend that could be tricked into running code if a user had it open and visited a malicious site. The business risk is localized but serious: code execution could compromise the user’s system and data.
Executive priority
Prioritize remediation where Elvish is used by technical staff, especially on systems with sensitive credentials or administrative access. This is not broadly internet-exposed by default, but successful exploitation could fully compromise a workstation.
Technical view
CVE-2021-41088 affects Elvish before 0.14.0. The `elvish -web` backend exposed a localhost endpoint intended for web UI code execution, but origin checks were insufficient. A malicious site could send requests to that endpoint when the user had the backend running.
Likely exposure
Exposure is most likely on developer or administrator workstations running Elvish below 0.14.0 with the web UI backend enabled. Source-built versions after 0.14.0 may also be exposed if the removed web UI was manually included.
Exploitation context
The supplied sources do not indicate active exploitation, and CISA KEV is false. Exploitation requires user interaction and a specific state: the web UI backend must be open while the user visits a malicious or compromised website.
Researcher notes
The issue maps to CWE-668 and CVSS 8.0. The key condition is cross-origin misuse of a localhost backend endpoint. Evidence supports affected Elvish versions before 0.14.0 and custom builds retaining the web UI, but does not establish exploitation in the wild.
Mitigation direction
- Upgrade to Elvish 0.14.0 or later where the web UI is no longer included.
- For older versions, remove the web UI component as described by the advisory.
- Check custom source builds for web, pkg/web, or pkg/prog/web inclusion.
- Avoid running `elvish -web` until vendor guidance is applied.
- Review vendor advisory and commit before choosing a backport approach.
Validation and detection
- Inventory Elvish versions and flag any installation below 0.14.0.
- Confirm whether any users run the web UI backend.
- Review custom builds for retained web UI source paths.
- Verify upgraded installations no longer include the web UI.
- Check endpoint exposure assumptions against actual workstation usage patterns.
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-668: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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-2021-41088 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
- High
- CVSS
- 8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
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:L/UI:R/S:C/C:H/I:H/A:H1.36Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/elves/elvish/security/advisories/GHSA-fpv6-f8jw-rc3rCVE reference · x_refsource_CONFIRM
- https://github.com/elves/elvish/commit/ccc2750037bbbfafe9c1b7a78eadd3bd16e81fe5CVE reference · x_refsource_MISC
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.
Exposure of Resource to Wrong Sphere
Exposure of Resource to Wrong Sphere represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.