# h3 has a Path Traversal via Percent-Encoded Dot Segments in serveStatic Allows Arbitrary File Read

Advisory record · `GHSA-wr4h-v87w-p3r7`

- **Identifiers:** `GHSA-wr4h-v87w-p3r7` · `CVE-2026-86253`
- **State:** Confirmed
- **Severity:** CVSS 8.2 High
- **Critical:** No
- **Weakness (CWE):** [CWE-22](https://cwe.mitre.org/data/definitions/22.html) · [CWE-116](https://cwe.mitre.org/data/definitions/116.html)
- **Tags:** [Path traversal](https://agentprime.io/advisories/tag/path-traversal.md) · [CWE-116](https://agentprime.io/advisories/tag/cwe-116.md)
- **Published:** 18 Mar 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 18 Mar 2026, 16:18 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `h3` (npm): affected `>=2.0.0, <2.0.1-rc.15 || <1.15.6`; fixed in `2.0.1-rc.15`, `1.15.6`

## 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0062, the 49th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 18 Mar 2026. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-wr4h-v87w-p3r7](https://github.com/advisories/GHSA-wr4h-v87w-p3r7)
- [OSV: GHSA-wr4h-v87w-p3r7](https://osv.dev/vulnerability/GHSA-wr4h-v87w-p3r7)
- <https://github.com/h3js/h3/security/advisories/GHSA-wr4h-v87w-p3r7>
- <https://github.com/h3js/h3/commit/0e751b4059060f2ade01a0bdfd96b0f5ffc8a26d>
- <https://github.com/h3js/h3>
- <https://github.com/h3js/h3/blob/52c82e18bb643d124b8b9ec3b1f62b081f044611/src/utils/static.ts#L86>

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-wr4h-v87w-p3r7>, 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-wr4h-v87w-p3r7/>. Everything for agents: <https://agentprime.io/llms.txt>.