# CVE-2021-25987: Hexo - Stored XSS

> A local attacker can inject arbitrary JavaScript into Hexo posts or tags, leading to stored XSS when the site is generated.

- **Severity:** Medium 5.0 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 30 Nov 2021
- **Updated:** 30 Apr 2025
- **Also known as:** GHSA-q54r-r9pr-w7qv

## What is CVE-2021-25987?

CVE-2021-25987 is a medium-severity cross-site scripting vulnerability in Hexo, published on 30 Nov 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Hexo versions 0.0.1 to 5.4.0 are vulnerable against stored XSS. The post “body” and “tags” don’t sanitize malicious javascript during web page generation. Local unprivileged attacker can inject arbitrary code.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-25987?

2 open source packages ship an affected version, including hexo. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hexo` | npm | From 0.0.1 | 6.0.0 |
| `hexo` | npm | From 0.0.1 | 6.0.0 |

Products: Hexo Hexo.

## How do I fix CVE-2021-25987?

Upgrade hexo to 6.0.0 or later.

## Is CVE-2021-25987 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-25987 exists.

## Other vulnerabilities in Hexo

- [CVE-2023-39584](https://insights.sbomify.com/CVE-2023-39584/): Hexo `include_code` has a path traversal (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25987 and fix it if it is affected.

What it is: CVE-2021-25987 is a medium-severity cross-site scripting vulnerability in Hexo, published on 30 Nov 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-25987 exists.

Affected packages and fixed versions:
- hexo (npm): affected from 0.0.1; fixed in 6.0.0
- hexo (npm): affected from 0.0.1; fixed in 6.0.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-25987/ (Markdown: https://insights.sbomify.com/CVE-2021-25987/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25987
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25987
- OSV: https://osv.dev/vulnerability/CVE-2021-25987

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25987/
Summaries are generated and may contain mistakes; the official description above is the record.