Security release 2026.1.1 of pretix

We have recently internally discovered a security issue inside pretix. We therefore just released versions 2026.1.1, 2025.10.2, and 2025.9.4 of pretix that fix this problem. It is strongly recommended that you update your installation as soon as possible, especially if you host pretix for third-party event organizers.

If you are a customer of our pretix Hosted service, the vulnerabilities are already fixed for you and you do not need to take action.

#1: Unsafe variable evaluation in emails [HIGH]

CVE ID: CVE-2026-2415

Emails sent by pretix can utilize placeholders that will be filled with customer data. For example, when {name} is used in an email template, it will be replaced with the buyer's name for the final email. This mechanism contained two security-relevant bugs:

1. It was possible to exfiltrate information about the pretix system through specially crafted placeholder names such as {{event.__init__.__code__.co_filename}}. This way, an attacker with the ability to control email templates (usually every user of the pretix backend) could retrieve sensitive information from the system configuration, including even database passwords. pretix does include mechanisms to prevent the usage of such malicious placeholders, however due to a mistake in the code, they were not fully effective for the email subject.

2. Placeholders in subjects and plain text bodies of emails were wrongfully evaluated twice. Therefore, if the first evaluation of a placeholder again contains a placeholder, this second placeholder was rendered. This allows the rendering of placeholders controlled by the ticket buyer, and therefore the exploitation of the first issue as a ticket buyer. Luckily, the only buyer-controlled placeholder available in pretix by default (that is not validated in a way that prevents the issue) is {invoice_company}, which is very unusual (but not impossible) to be contained in an email subject template. In addition to broadening the attack surface of the first issue, this could theoretically also leak information about an order to one of the attendees within that order. However, we also consider this scenario very unlikely under typical conditions.

We have scanned all available data sources (such as the logs kept by the system) and were unable to identify any indications that the security vulnerability was actually exploited on our pretix Hosted installation. We therefore assume that it has not been discovered by third parties and no unauthorized access to the information of our server has taken place and that the risk is now mitigated. However, due to the nature of the security vulnerability, we cannot rule this out with absolute certainty.

Out of caution, we recommend that you rotate all passwords and API keys contained in your pretix.cfg file.

Severity rating: Since this bug can be used to exfiltrate highly sensitive information, we consider the severity to be high.

Affected versions: All currently supported versions of pretix after 4.16.0 (estimated) and prior to 2026.1.1 (except the fixed versions listed below) are affected.

Affected plugins: Similar bugs affect two pretix Enterprise plugins, for which we have also issued security updates:

• pretix-doistep (CVE-2026-2451, fixed in 1.3.2)
• pretix-newsletter (CVE-2026-2452, fixed in 2.0.1 and 1.6.3)

Fixed versions

We just released updates for the last three stable versions on PyPI that fix problem #1. If you run a pretix installation older than 2025.9, please upgrade to a recent version now.

• 2026.1.1
• 2025.10.2
• 2025.9.4

The new docker images will appear on Docker Hub over the next few hours.

We strongly recommend that you always run the latest version of pretix, as every release contains useful and important bug fixes, even if they are not security related.

If you want to keep updated about bugfix and security releases, you should follow this blog closely. A RSS feed is available and we also announce every blogpost on Mastodon.

We take the security of our product very seriously and always go the extra mile to make sure you stay safe. As we are humans, security issues unfortunately still might occur from time to time. We do everything we can to find and fix them as timely as we can. If you notice any security problems or have any questions on this topic, please contact us in private at security@pretix.eu. We will always treat your message with the appropriate priority.