CVE-2026-13603 SSRF with API key leak in pretix-oppwa
Attackers can exploit improper URL validation to force server-side requests to arbitrary hosts, leaking API keys and accessing payment provider data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-13603?
CVE-2026-13603 is a critical server-side request forgery vulnerability in pretix-oppwa, published on 1 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-13603?
How do I fix CVE-2026-13603?
No fix has been published for CVE-2026-13603 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-13603 being exploited?
There is no known exploitation of CVE-2026-13603 in the wild and no public exploit code.
Sources
Also known as GHSA-29fq-jc8m-8rq2.