CVE-2026-86251
8.2
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
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| h3js | h3 | 0 < 1.15.9 | affected |
| h3js | h3 | 1.15.9 | unaffected |
Weaknesses
- CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
References
- https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhw
- https://www.vulncheck.com/advisories/h3-before-1.15.9-path-traversal-via-double-decoding
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