dbcve.org
Improper Input ValidationWeakness · CWE-20

CVE-2026-13603

CRITICAL · 9.0 CVSS v4.0 Published 2026-07-01
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
99/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is a Server-Side Request Forgery (SSRF) vulnerability in the pretix-oppwa payment plugin. The plugin insecurely concatenates a user-controlled 'resourcePath' query parameter from the payment provider's return URL to the API base domain without validation and without a trailing slash on the baseUrl. Attackers can inject a malicious resourcePath to redirect API requests (including the Oppwa API key) to an attacker-controlled server, resulting in credential theft.

MitigationUpdate to the patched version of pretix-oppwa immediately and rotate all exposed API access tokens with the payment provider as recommended.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if pretix-oppwa plugin is installed
    Check the pretix plugins directory or plugin configuration file for 'pretix-oppwa' or 'oppwa' entry. Common locations: pretix control panel > Plugins > Payment Plugins list, or check installed packages with 'pip list | grep pretix-oppwa'
    Affected if The plugin appears in the installed plugins list or package manager output
  2. Determine the installed version of pretix-oppwa
    Run 'pip show pretix-oppwa' or check the plugin's __init__.py or setup.py for the version string. Compare the version number to the patched version provided by the vendor.
    Affected if The installed version is lower than the patched version released for CVE-2026-13603
  3. Verify the plugin is active and configured
    Check pretix admin panel > Settings > Payment > OPPWA (oppwa) is enabled, or inspect the database table for active payment providers. The vulnerability only applies when the plugin is enabled.
    Affected if The oppwa payment plugin shows as enabled or active in the payment provider configuration
  4. Check for API key configuration
    Inspect the plugin settings or configuration file for stored Oppwa API keys. The vulnerability allows exfiltration of these credentials when the plugin processes return URLs.
    Affected if Oppwa API credentials are configured and stored in the plugin settings

A user is affected if the pretix-oppwa plugin is installed, enabled, and runs a version prior to the patched release for CVE-2026-13603.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update to the patched version of pretix-oppwa immediately and rotate all exposed API access tokens with the payment provider as recommended.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-13603 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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