Security readout for executives and security teams
Plain-English summary
Hexo sites generated with vulnerable versions can permanently include malicious JavaScript in posts or tags. The business risk is that visitors to a generated site may run attacker-controlled code in their browsers, affecting trust, session data, or content integrity. The provided sources rate this as medium severity, not a broad remote server takeover.
Executive priority
Treat this as a moderate-priority website integrity issue. Prioritize remediation for public Hexo sites, sites with multiple content contributors, or workflows accepting external submissions. Lower urgency applies to single-author, internally viewed sites with trusted content only.
Technical view
CVE-2021-25987 is a CWE-79 stored XSS in Hexo versions 0.0.1 through 5.4.0. Post body and tag content were not sufficiently sanitized during page generation, allowing arbitrary JavaScript to be embedded into generated pages. The CVSS vector is local attack, low complexity, user interaction required, changed scope, low confidentiality and integrity impact.
Likely exposure
Exposure is most likely where Hexo 0.0.1 through 5.4.0 is used and untrusted or lower-privileged users can influence post bodies, tags, or source content before static pages are generated.
Exploitation context
The provided record does not cite active exploitation and marks KEV false. Practical exploitation requires malicious content to enter the Hexo content pipeline and a user to view the generated page. Evidence provided is incomplete on exploit prevalence and fixed release details.
Researcher notes
The key uncertainty is remediation detail: the bundle references a Hexo commit but does not name a fixed version. Do not assume exploit activity from this data. Focus validation on affected version range, content authorship paths, and whether generated pages preserve unsafe JavaScript from body or tags.
Mitigation direction
- Inventory Hexo usage and identify versions 0.0.1 through 5.4.0.
- Check Hexo vendor guidance and upgrade to a fixed release if available.
- Restrict post and tag editing to trusted users only.
- Review generated pages before publishing when accepting contributed content.
- Remove or sanitize suspicious script-bearing content from posts and tags.
Validation and detection
- Review package manifests and lockfiles for the installed Hexo version.
- Confirm whether any site generation pipeline uses Hexo 0.0.1 through 5.4.0.
- Audit posts and tags for unexpected JavaScript-bearing content.
- Test generated pages in a safe staging environment for unintended script execution.
- Verify access controls around content authorship and publishing workflows.
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 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-2021-25987 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
- 5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/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:L/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N1.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5MediumVector: CVSS:3.1/AV:L/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/hexojs/hexo/commit/5170df2d3fa9c69e855c4b7c2b084ebfd92d5200CVE reference · x_refsource_MISC
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25987CVE 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.