CVE-2026-86251
mediumh3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility.
h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences (e.g. %252e%252e) to be decoded to %2e%2e, which survives resolveDotSegments() because that function only checks for literal '.' characters. When the resulting asset ID is resolved by URL-based backends (CDN, S3, object storage), %2e%2e is interpreted as '..' per RFC 3986, enabling path traversal to read arbitrary files from the backend.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhw disclosure@vulncheck.com
- https://www.vulncheck.com/advisories/h3-before-1.15.9-path-traversal-via-double-decoding disclosure@vulncheck.com
- https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhw 134c704f-9b21-4f2e-91b3-4a467353bcc0