# CVE-2026-53758: Emlog: Stored XSS via Parsedown Markdown Processing - Raw HTML Not Sanitized

> Attackers can inject malicious scripts via Markdown content in Emlog, leading to stored XSS affecting all site visitors.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Sep 2026
- **Updated:** 9 Sep 2026
- **Also known as:** GHSA-35vc-2gv4-mw77

## What is CVE-2026-53758?

CVE-2026-53758 is a high-severity cross-site scripting vulnerability in emlog, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Emlog is an open source website building system. In versions 2.6.29 and prior, article content is processed by Parsedown without enabling safe mode, which means raw HTML including <script> tags embedded in Markdown is passed through unescaped. The output is rendered with no additional sanitization, resulting in stored XSS visible to all site visitors. At time of publication, there are no publicly known patches.

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

## Which versions are affected by CVE-2026-53758?


## How do I fix CVE-2026-53758?

No fix has been published for CVE-2026-53758 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-53758 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53758 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53758 and fix it if it is affected.

What it is: CVE-2026-53758 is a high-severity cross-site scripting vulnerability in emlog, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53758 exists.

Affected product: emlog. 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-2026-53758/ (Markdown: https://insights.sbomify.com/CVE-2026-53758/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53758
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53758
- OSV: https://osv.dev/vulnerability/CVE-2026-53758

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-53758/
Summaries are generated and may contain mistakes; the official description above is the record.