# CVE-2026-71236: Grocy - Stored XSS via HTMLPurifier Output Double-Decode

> Attackers can inject malicious scripts into Grocy by exploiting a double-decoding flaw in the API request body parser, potentially leading to session hijacking or code execution.

- **Severity:** High 8.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A: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:** 5 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** GHSA-c924-wcfj-cr8j

## What is CVE-2026-71236?

CVE-2026-71236 is a high-severity cross-site scripting vulnerability in grocy, published on 5 Aug 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

Grocy's API request-body parser (controllers/Api/BaseApiController.php, GetParsedAndFilteredRequestBody) purifies incoming field values with HTMLPurifier, then manually reverses HTML-entity encoding of the resulting output by replacing &amp;lt;, &amp;gt;, and &amp;amp; back to <, >, and & immediately after purification.

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

## Which versions are affected by CVE-2026-71236?


## How do I fix CVE-2026-71236?

No fix has been published for CVE-2026-71236 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-71236 being exploited?

There is no known exploitation of CVE-2026-71236 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71236 and fix it if it is affected.

What it is: CVE-2026-71236 is a high-severity cross-site scripting vulnerability in grocy, published on 5 Aug 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-2026-71236 in the wild and no public exploit code.

Affected product: grocy. 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-2026-71236/ (Markdown: https://insights.sbomify.com/CVE-2026-71236/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71236
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71236
- OSV: https://osv.dev/vulnerability/CVE-2026-71236

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-71236/
Summaries are generated and may contain mistakes; the official description above is the record.