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CVE PROGRAM SOURCE RECORD8.2 High

CVE-2026-86251

h3 before 1.15.9 Path Traversal via Double Decoding

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Status
Published
Published
Updated
Assigning organization
VulnCheck

Description

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 products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

h3js h3

Default version status: unaffected

  • 0 to < 1.15.9affected
  • 1.15.9unaffected
pkg:npm/h3

References