# CVE-2026-89411: Paymattic < 4.6.26 - Unauthenticated Payment Bypass via Unbound Stripe PaymentIntent

> Unauthenticated attackers can mark arbitrary pending orders as paid by confirming a smaller Stripe payment, bypassing payment verification in Paymattic.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A: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 Sep 2026
- **Updated:** 28 Sep 2026
- **Also known as:** GHSA-xhxc-69hm-mqvf

## What is CVE-2026-89411?

CVE-2026-89411 is a medium-severity vulnerability in Unknown Paymattic, published on 28 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Paymattic WordPress plugin from 4.6.20 before 4.6.26 does not verify that a confirmed Stripe payment belongs to the order it is applied to, allowing unauthenticated users to mark an arbitrary pending order as paid by confirming a smaller payment of their own against it.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-89411?


## How do I fix CVE-2026-89411?

No fix has been published for CVE-2026-89411 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-89411 being exploited?

There is no known exploitation of CVE-2026-89411 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89411 and fix it if it is affected.

What it is: CVE-2026-89411 is a medium-severity vulnerability in Unknown Paymattic, published on 28 Sep 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-2026-89411 in the wild and no public exploit code.

Affected product: Unknown Paymattic. 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-2026-89411/ (Markdown: https://insights.sbomify.com/CVE-2026-89411/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89411
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89411
- OSV: https://osv.dev/vulnerability/CVE-2026-89411

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89411/
Summaries are generated and may contain mistakes; the official description above is the record.