# mpp Tempo keys its pre-broadcast dedup reserve on the caller-supplied transaction encoding, so a re-encoded signed transaction reserves a second slot

Advisory record · `GHSA-8x7x-5j8g-8hcx`

- **Identifiers:** `GHSA-8x7x-5j8g-8hcx` · `CVE-2026-88255` · `EEF-CVE-2026-88255`
- **State:** Confirmed
- **Severity:** CVSS 6.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-1289](https://cwe.mitre.org/data/definitions/1289.html)
- **Tags:** [CWE-1289](https://agentprime.io/advisories/tag/cwe-1289.md)
- **Published:** 16 Sept 2026
- **Updated:** 16 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 16 Sept 2026, 08:24 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `mpp` (Hex): affected `>=0.2.0, <0.16.2`; fixed in `0.16.2`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.3 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`, from CNA (EEF)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0052, the 44th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:25 UTC: First seen by agentprime
- 31 Oct 2026, 15:25 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/EEF-CVE-2026-88255)

## Sources

- [GitHub Advisory Database: GHSA-8x7x-5j8g-8hcx](https://github.com/advisories/GHSA-8x7x-5j8g-8hcx)
- [OSV: GHSA-8x7x-5j8g-8hcx](https://osv.dev/vulnerability/GHSA-8x7x-5j8g-8hcx)
- <https://github.com/ZenHive/mpp/security/advisories/GHSA-8x7x-5j8g-8hcx>
- <https://cna.erlef.org/cves/CVE-2026-88255.html>
- <https://github.com/ZenHive/mpp/commit/f8904666061fbab695874856d8fcd02c471dfe1b>
- <https://github.com/ZenHive/mpp/commit/e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43>
- <https://hex.pm/packages/mpp>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-8x7x-5j8g-8hcx>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-8x7x-5j8g-8hcx/>. Everything for agents: <https://agentprime.io/llms.txt>.