CVE-2026-13603: CWE-20 Improper input validation in pretix pretix-oppwa
The payment integration pretix-oppwa provides support for the payment providers VR Payment, Hobex, and potentially others based on Oppwa's technology. The integration of Oppwa, following their official documentation, includes a step where the user is redirected from the payment provider back to our system with a query parameter like ?resourcePath=/v1/checkouts/{checkoutId}/payment in the URL. Our system is then supposed to fetch the status of the transaction from the URL given by baseUrl + resourcePath. Our plugin pretix-oppwa did so insecurely by concatenating the parameter form the URL to the base domain of the API without further validation and, critically, without a / at the end of the baseUrl. Therefore, an attacker could inject a resourcePath argument in a way that causes pretix to call a different server instead. Since the request includes the access token (API key) of the Oppwa account, this would leak the access token, giving access to data contained in the payment provider's system. This is fixed with the release today by strictly validating the given API URL. After installing the update, we recommend asking your payment provider for a new access token and updating it in pretix.
AI Analysis
Technical Summary
The pretix-oppwa plugin integrates payment providers using Oppwa's technology by redirecting users back with a query parameter 'resourcePath' indicating the API endpoint to fetch transaction status. The plugin concatenates this parameter directly to the base API URL without validating the input or ensuring a trailing slash on the base URL. This improper input validation allows an attacker to craft a malicious 'resourcePath' that causes the system to send API requests, including the sensitive access token, to an attacker-controlled server. This vulnerability (CWE-20) leads to leakage of the Oppwa API key and unauthorized access to payment provider data. The vulnerability affects versions prior to 1.4.4 and is resolved by adding strict validation of the API URL in version 1.4.4. After updating, it is recommended to obtain a new access token from the payment provider.
Potential Impact
Exploitation of this vulnerability can result in leakage of the Oppwa API access token used by pretix-oppwa, allowing an attacker to access sensitive data within the payment provider's system. This compromises the confidentiality of payment transaction information and potentially other sensitive data accessible via the API. The vulnerability does not require user interaction or privileges and can be triggered remotely, making it critical in severity.
Mitigation Recommendations
Update pretix-oppwa to version 1.4.4 or later, which includes strict validation of the API URL to prevent malicious redirection. After applying the update, request a new access token from your payment provider and update it in the pretix configuration to invalidate any potentially leaked credentials. Patch status is not explicitly stated as 'official-fix' but the fix is included in version 1.4.4. No other mitigations are indicated.
CVE-2026-13603: CWE-20 Improper input validation in pretix pretix-oppwa
Description
The payment integration pretix-oppwa provides support for the payment providers VR Payment, Hobex, and potentially others based on Oppwa's technology. The integration of Oppwa, following their official documentation, includes a step where the user is redirected from the payment provider back to our system with a query parameter like ?resourcePath=/v1/checkouts/{checkoutId}/payment in the URL. Our system is then supposed to fetch the status of the transaction from the URL given by baseUrl + resourcePath. Our plugin pretix-oppwa did so insecurely by concatenating the parameter form the URL to the base domain of the API without further validation and, critically, without a / at the end of the baseUrl. Therefore, an attacker could inject a resourcePath argument in a way that causes pretix to call a different server instead. Since the request includes the access token (API key) of the Oppwa account, this would leak the access token, giving access to data contained in the payment provider's system. This is fixed with the release today by strictly validating the given API URL. After installing the update, we recommend asking your payment provider for a new access token and updating it in pretix.
CVSS v4.0
Score 9.0critical
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The pretix-oppwa plugin integrates payment providers using Oppwa's technology by redirecting users back with a query parameter 'resourcePath' indicating the API endpoint to fetch transaction status. The plugin concatenates this parameter directly to the base API URL without validating the input or ensuring a trailing slash on the base URL. This improper input validation allows an attacker to craft a malicious 'resourcePath' that causes the system to send API requests, including the sensitive access token, to an attacker-controlled server. This vulnerability (CWE-20) leads to leakage of the Oppwa API key and unauthorized access to payment provider data. The vulnerability affects versions prior to 1.4.4 and is resolved by adding strict validation of the API URL in version 1.4.4. After updating, it is recommended to obtain a new access token from the payment provider.
Potential Impact
Exploitation of this vulnerability can result in leakage of the Oppwa API access token used by pretix-oppwa, allowing an attacker to access sensitive data within the payment provider's system. This compromises the confidentiality of payment transaction information and potentially other sensitive data accessible via the API. The vulnerability does not require user interaction or privileges and can be triggered remotely, making it critical in severity.
Mitigation Recommendations
Update pretix-oppwa to version 1.4.4 or later, which includes strict validation of the API URL to prevent malicious redirection. After applying the update, request a new access token from your payment provider and update it in the pretix configuration to invalidate any potentially leaked credentials. Patch status is not explicitly stated as 'official-fix' but the fix is included in version 1.4.4. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- rami.io
- Date Reserved
- 2026-06-29T08:26:51.607Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4517f827e9c7971989279d
Added to database: 07/01/2026, 13:36:56 UTC
Last enriched: 07/01/2026, 13:51:37 UTC
Last updated: 07/01/2026, 14:36:58 UTC
Views: 3
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.