# GHSA-fxc9-7j2w-vx54: mpp has multiple payment bypass and griefing vulnerabilities

> Attackers can bypass payment checks, replay transactions, and manipulate fee payers in the mpp library, leading to financial loss and service abuse.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Mar 2026

## What is GHSA-fxc9-7j2w-vx54?

GHSA-fxc9-7j2w-vx54 is a vulnerability in mpp, published on 29 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

### Impact
Multiple vulnerabilities were discovered which allowed for undesirable behaviors, including:
- Performing free `tempo/charge` requests
- Replaying existing `tempo/charge` requests
- Performing free `tempo/session` requests
- Piggybacking off existing `tempo/session` channels
- Griefing existing `tempo/session` channels
- Manipulate the fee payer of a `tempo/charge` or `tempo/session` handler into paying for requests
- Replaying existing `stripe/charge` requests

### Patches
The issues are patched in 0.8.0

### Workarounds
There are no workarounds available for these vulnerabilities

## Which versions are affected by GHSA-fxc9-7j2w-vx54?

2 open source packages ship an affected version, including mpp.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mpp` | crates.io | All versions | 0.8.0 |
| `mpp` | crates.io | All versions | 0.8.0 |

## How do I fix GHSA-fxc9-7j2w-vx54?

Upgrade mpp to 0.8.0 or later.

## Is GHSA-fxc9-7j2w-vx54 being exploited?

There is no known exploitation of GHSA-fxc9-7j2w-vx54 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-fxc9-7j2w-vx54 and fix it if it is affected.

What it is: GHSA-fxc9-7j2w-vx54 is a vulnerability in mpp, published on 29 Mar 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 GHSA-fxc9-7j2w-vx54 in the wild and no public exploit code.

Affected packages and fixed versions:
- mpp (crates.io): affected all versions; fixed in 0.8.0
- mpp (crates.io): affected all versions; fixed in 0.8.0

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/GHSA-fxc9-7j2w-vx54/ (Markdown: https://insights.sbomify.com/GHSA-fxc9-7j2w-vx54/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-fxc9-7j2w-vx54

---
From sbomify Insights: https://insights.sbomify.com/GHSA-fxc9-7j2w-vx54/
Summaries are generated and may contain mistakes; the official description above is the record.