# Plug: quadratic-time decoding of nested query/body parameters enables denial of service

Advisory record · `GHSA-j43x-5hjq-rgxf`

- **Identifiers:** `GHSA-j43x-5hjq-rgxf` · `CVE-2026-54892` · `EEF-CVE-2026-54892`
- **State:** Confirmed
- **Severity:** CVSS 8.7 High
- **Critical:** No
- **Weakness (CWE):** [CWE-407](https://cwe.mitre.org/data/definitions/407.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 23 Sept 2026
- **Updated:** 23 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 23 Sept 2026, 14:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `plug` (Hex): affected `>=1.15.0, <1.15.5 || >=1.16.0, <1.16.4 || >=1.17.0, <1.17.2 || >=1.18.0, <1.18.3 || >=1.19.0, <1.19.3`; fixed in `1.15.5`, `1.16.4`, `1.17.2`, `1.18.3`, `1.19.3`

## 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0089, the 59th 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/GHSA-j43x-5hjq-rgxf)

## Sources

- [GitHub Advisory Database: GHSA-j43x-5hjq-rgxf](https://github.com/advisories/GHSA-j43x-5hjq-rgxf)
- [OSV: GHSA-j43x-5hjq-rgxf](https://osv.dev/vulnerability/GHSA-j43x-5hjq-rgxf)
- <https://github.com/elixir-plug/plug/security/advisories/GHSA-j43x-5hjq-rgxf>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-54892>
- <https://github.com/elixir-plug/plug/commit/9c5d37c440eaae92869eed7c014c47266744fadb>
- <https://github.com/elixir-plug/plug/commit/a61124aa625d819a218fb07f90afbac8aa85eb0e>
- <https://github.com/elixir-plug/plug/commit/c317d08fdcf96e17931f7419275b2b8c4bf3e951>
- <https://github.com/elixir-plug/plug/commit/d4e5568392a4b29e545b91e12e87d6098f976145>
- <https://github.com/elixir-plug/plug/commit/d737eb236f17e31a36290e39f9ef3cd86a1343bd>
- <https://cna.erlef.org/cves/CVE-2026-54892.html>
- <https://github.com/elixir-plug/plug>
- <https://github.com/elixir-plug/plug/blob/v1.19.3/CHANGELOG.md#v1193-2026-06-23>
- <https://osv.dev/vulnerability/EEF-CVE-2026-54892>

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-j43x-5hjq-rgxf>, 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-j43x-5hjq-rgxf/>. Everything for agents: <https://agentprime.io/llms.txt>.