CVE-2026-86251h3 before 1.15.9 Path Traversal via Double Decoding
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It affects h3js h3. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 5.9 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weakness (CWE)
- CWE-22
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Awaiting Analysis
- Record last updated
- Sep 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
h3js h3 h3js:h3 (from the name) | before 1.15.9; 1.15.9 not affected | CNA record |
References
- https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhwvendor-advisory
- https://www.vulncheck.com/advisories/h3-before-1.15.9-path-traversal-via-double-decodingthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.