# CVE-2026-58487: HedgeDoc: Stored HTML injection via email local-part

> Attackers can inject arbitrary HTML into HedgeDoc pages via crafted email addresses, altering content and embedding malicious resources for other users.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 13 Jul 2026
- **Updated:** 15 Jul 2026
- **Also known as:** GHSA-6c2w-8w96-3pcv

## What is CVE-2026-58487?

CVE-2026-58487 is a medium-severity cross-site scripting vulnerability in hedgedoc, published on 13 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

HedgeDoc is an open source, real-time, collaborative, markdown notes application. Prior to version 1.11.0, due to unsafe handling of the local-part of registered email addresses, HedgeDoc was vulnerable to stored HTML Injection through its publish and slide views. An attacker could register a specially crafted email address and inject arbitrary HTML into pages viewed by other users. HedgeDoc  accepted RFC 5321 quoted-string local-parts in email addresses during registration. The local-part was then reused as the user's display name without escaping and rendered into HTML in multiple places, including publish and slide views as well as the collaborative editor. An attacker could break out of an HTML attribute and inject arbitrary markup into the page. While the deployed Content-Security-Policy prevented straightforward inline JavaScript execution, the injected HTML was still sufficient to alter page content and embed attacker-controlled resources such as cross-origin iframes. This issue was fixed in version 1.11.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2026-58487?


## How do I fix CVE-2026-58487?

No fix has been published for CVE-2026-58487 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-58487 being exploited?

There is no known exploitation of CVE-2026-58487 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58487 and fix it if it is affected.

What it is: CVE-2026-58487 is a medium-severity cross-site scripting vulnerability in hedgedoc, published on 13 Jul 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-58487 in the wild and no public exploit code.

Affected product: hedgedoc. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-58487/ (Markdown: https://insights.sbomify.com/CVE-2026-58487/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58487
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58487
- OSV: https://osv.dev/vulnerability/CVE-2026-58487

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-58487/
Summaries are generated and may contain mistakes; the official description above is the record.