# CVE-2026-77129: Server-Side Template Injection in extension "Event management and registration" (sf_event_mgt)

> Authenticated backend users can inject Fluid template code to disclose data or execute TypoScript objects in the Event management extension.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** GHSA-j8g2-q9pf-89w3

## What is CVE-2026-77129?

CVE-2026-77129 is a high-severity code injection vulnerability in TYPO3 Extension "Event management and registration", published on 25 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The extension passes an editor-configurable email subject string directly into a Fluid template source without restriction. A backend user with edit access to the event plugin or Backend Module can supply Fluid ViewHelper syntax in this field to disclose sensitive data or execute TypoScript content objects. Exploitation of this issue requires an authenticated backend account with edit access to the event registration plugin or backend module.

Weakness: CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine)

## Which versions are affected by CVE-2026-77129?


## How do I fix CVE-2026-77129?

No fix has been published for CVE-2026-77129 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-77129 being exploited?

There is no known exploitation of CVE-2026-77129 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77129 and fix it if it is affected.

What it is: CVE-2026-77129 is a high-severity code injection vulnerability in TYPO3 Extension "Event management and registration", published on 25 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-77129 in the wild and no public exploit code.

Affected product: TYPO3 Extension "Event management and registration". 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-2026-77129/ (Markdown: https://insights.sbomify.com/CVE-2026-77129/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77129
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77129
- OSV: https://osv.dev/vulnerability/CVE-2026-77129

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77129/
Summaries are generated and may contain mistakes; the official description above is the record.