# CVE-2026-41426: pretalx: Email injection via unescaped user-controlled placeholders in pretalx mail templates

> An attacker can inject malicious HTML into email templates to send phishing emails from the legitimate sender address, bypassing email authentication checks.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Apr 2026
- **Updated:** 25 Apr 2026
- **Also known as:** GHSA-jm8c-9f3j-4378, PYSEC-2026-109

## What is CVE-2026-41426?

CVE-2026-41426 is a medium-severity cross-site scripting vulnerability in pretalx, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

pretalx is a conference planning tool. Prior to 2026.1.0, an unauthenticated attacker can send arbitrary HTML-rendered emails from a pretalx instance's configured sender address by embedding malformed HTML or markdown link syntax in a user-controlled template placeholder such as the account display name. The most direct vector is the password-reset flow: the attacker registers an account with a malicious name, enters the victim's email address, and triggers a password reset. The resulting email is delivered from the event's legitimate sender address and passes SPF/DKIM/DMARC validation, making it a ready-made phishing vector. This vulnerability is fixed in 2026.1.0.

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-2026-41426?

3 open source packages ship an affected version, including pretalx. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pretalx` | PyPI | All versions | 2026.1.0 |
| `pretalx` | PyPI | All versions | 2026.1.0 |
| `pretalx` | PyPI | All versions | 2026.1.0 |

Products: Pretalx Pretalx.

## How do I fix CVE-2026-41426?

Upgrade pretalx to 2026.1.0 or later.

## Is CVE-2026-41426 being exploited?

There is no known exploitation of CVE-2026-41426 in the wild and no public exploit code.

## Other vulnerabilities in pretalx

- [CVE-2026-41241](https://insights.sbomify.com/CVE-2026-41241/): pretalx: Stored cross-site scripting in organiser search typeahead (high 8.7)
- [CVE-2023-28459](https://insights.sbomify.com/CVE-2023-28459/): pretalx vulnerable to path traversal in HTML export (medium 6.5)
- [CVE-2023-28458](https://insights.sbomify.com/CVE-2023-28458/): pretalx allows path traversal in HTML export (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-41426 and fix it if it is affected.

What it is: CVE-2026-41426 is a medium-severity cross-site scripting vulnerability in pretalx, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-41426 in the wild and no public exploit code.

Affected packages and fixed versions:
- pretalx (PyPI): affected all versions; fixed in 2026.1.0
- pretalx (PyPI): affected all versions; fixed in 2026.1.0
- pretalx (PyPI): affected all versions; fixed in 2026.1.0

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-2026-41426/ (Markdown: https://insights.sbomify.com/CVE-2026-41426/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41426
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41426
- OSV: https://osv.dev/vulnerability/CVE-2026-41426

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-41426/
Summaries are generated and may contain mistakes; the official description above is the record.