CVE-2026-13602
Received Received - Intake

Session Parameter Manipulation in Pretix Payment Plugins

Publication date: 2026-07-01

Last updated on: 2026-07-01

Assigner: rami.io

Description
We found a chain of combining multiple weaknesses in the product that could allow an attacker to become any user in the backend and access any data: * The payment integration plugins Stripe (included in the core system), pretix-mollie, pretix-oppwa, pretix-bitpay, pretix-payone, pretix-secuconnect, pretix-sofort, and pretix-saferpay contain a code path that is intended for the transport of session parameters from a tab with isolated cookies (e.g. in the pretix widget) to a new tab. For this purpose, a set of session parameters is cryptographically signed and then passed to the new tab as a URL parameter. The plugins perform no further validation of the session parameters, other than the cryptographic signature being valid. This is fixed with the releases issued today by strictly validating that no session parameters outside of the scope of the respective plugin may be set. * An unrelated feature in the core system is used to generate redirect links that obfuscate any Referer headers for outgoing links to prevent leakage of secrets in URLs. This redirect page also requires cryptographically signed parameters. Unfortunately, it uses the same key and salt for the signature as the previously mentioned feature in the payment integration plugins. A motivated attacker with access to at least one event in the backend can trick the system into cryptographically signing arbitrary content using specially crafted links. In combination with the previous issue, the attacker could use this to set and modify arbitrary parameters on their user session by injecting the signed parameters into the feature of the payment providers. This is fixed with the releases issued today by using different salts for the signature for each plugin and feature. * A third, unrelated feature in the core system is used for admin users to act on behalf of another user, mostly for debugging purposes. With being able to insert arbitrary parameters into a session, an attacker can abuse this feature to change their session from their actual user to any user in the system by guessing a valid user ID. This is fixed with the release today by requiring unguessable information to be contained in the session of the user to switch to.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-07-01
Last Modified
2026-07-01
Generated
2026-07-01
AI Q&A
2026-07-01
EPSS Evaluated
N/A
NVD
CVE-2026-13602
EUVD
EUVD-2026-40995

Affected Vendors & Products

Showing 8 associated CPEs
Vendor Product Version / Range
pretix pretix *
pretix pretix-mollie *
pretix pretix-oppwa *
pretix pretix-bitpay *
pretix pretix-payone *
pretix pretix-secuconnect *
pretix pretix-sofort *
pretix pretix-saferpay *

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-20 The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
CWE-323 Nonces should be used for the present occasion and only once.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability involves a chain of weaknesses in the pretix system and its payment integration plugins that allows an attacker to impersonate any user in the backend and access any data.

The issue arises because several payment plugins (Stripe, pretix-mollie, pretix-oppwa, pretix-bitpay, pretix-payone, pretix-secuconnect, pretix-sofort, and pretix-saferpay) pass session parameters between browser tabs using cryptographically signed URL parameters. However, these plugins only verify the signature and do not validate the scope of the session parameters.

An unrelated core system feature generates redirect links with cryptographically signed parameters to obfuscate Referer headers. Unfortunately, it uses the same key and salt for signing as the payment plugins, allowing an attacker with backend event access to craft links that sign arbitrary content.

By combining these issues, an attacker can inject and modify arbitrary session parameters, including switching their session to impersonate any user by guessing user IDs, abusing an admin feature intended for debugging.

The vulnerability is fixed by strictly validating session parameters per plugin, using different salts for signatures, and requiring unguessable information for user switching.

Impact Analysis

This vulnerability can have severe impacts as it allows an attacker to become any user in the backend system.

By impersonating other users, an attacker can access any data accessible to those users, potentially including sensitive or confidential information.

This unauthorized access can lead to data breaches, loss of data integrity, and unauthorized actions performed on behalf of legitimate users.

Mitigation Strategies

The vulnerability is fixed with releases issued on the publication date. Immediate mitigation steps include updating the affected pretix core system and all related payment integration plugins (Stripe, pretix-mollie, pretix-oppwa, pretix-bitpay, pretix-payone, pretix-secuconnect, pretix-sofort, and pretix-saferpay) to the fixed versions.

These updates implement strict validation of session parameters, use different salts for cryptographic signatures for each plugin and feature, and require unguessable information in sessions to prevent unauthorized user switching.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-13602. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart