# CVE-2026-18029: Insufficient validation of payment status in pretix-girosolution

> Attackers can reuse valid payment responses to obtain multiple tickets for a single payment, bypassing payment validation in the pretix GiroSolution integration.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** GHSA-f83j-v8r3-vfhv

## What is CVE-2026-18029?

CVE-2026-18029 is a medium-severity vulnerability in pretix-girosolution, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Our payment integration with GiroCheckout did not properly validate 
payment status responses. An attacker could use a successful payment 
status response from one payment and supply it to the system for a 
different payment, gaining access to multiple valid tickets with only 
one payment.

Weakness: CWE-841 (Improper Enforcement of Behavioral Workflow)

## Which versions are affected by CVE-2026-18029?


## How do I fix CVE-2026-18029?

No fix has been published for CVE-2026-18029 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-18029 being exploited?

There is no known exploitation of CVE-2026-18029 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18029 and fix it if it is affected.

What it is: CVE-2026-18029 is a medium-severity vulnerability in pretix-girosolution, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-18029 in the wild and no public exploit code.

Affected product: pretix-girosolution. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-18029/ (Markdown: https://insights.sbomify.com/CVE-2026-18029/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18029
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18029
- OSV: https://osv.dev/vulnerability/CVE-2026-18029

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18029/
Summaries are generated and may contain mistakes; the official description above is the record.