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CVE-2026-86253— h3 before 1.15.6 Path Traversal via Percent-Encoded Dot Segments

Quick assessment

Affected
h3js h3
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

h3（npm 包）版本 ≤ 2.0.1-rc.14 中的 函数存在路径遍历漏洞。在 Node.js 部署环境中， 未进行规范化处理，导致百分号编码的点段（如 ）在被传入 解码为 序列时未经过净化处理。未认证的远程攻击者可以通过向由 提供的端点发送精心构造的请求，读取目标静态目录之外的任意文件。该漏洞已在版本 1.15.6 和 2.0.1-rc.15 中修复。

CVSS 5.9 · Medium

Affected Version Matrix 4

VendorProduct Version RangeStatus
h3js h3 < 1.15.6 affected
1.15.6 unaffected
2.0.0-beta.0< 2.0.1-rc.15 affected
2.0.1-rc.15 unaffected
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I. Basic Information for CVE-2026-86253

Vulnerability Information
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Vulnerability Title
h3 before 1.15.6 Path Traversal via Percent-Encoded Dot Segments
Source: CVE Program / CVE List V5
Vulnerability Description
h3 (npm package) versions <= 2.0.1-rc.14 contain a path traversal vulnerability in serveStatic(). On Node.js deployments, event.url.pathname is not normalized, so percent-encoded dot segments (%2e%2e) are passed to decodeURI() and decoded to ../ sequences without sanitization. An unauthenticated remote attacker can send crafted requests to endpoints served by serveStatic() to read arbitrary files outside the intended static directory. Fixed in 1.15.6 and 2.0.1-rc.15.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
h3js h3 0 ~ 1.15.6 -

II. Public POCs for CVE-2026-86253

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III. Intelligence Information for CVE-2026-86253

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Vendor Advisories for CVE-2026-86253 (2)

Same Patch Batch · h3js · 2026-09-06 · 5 CVEs total

CVE-2026-86250 7.5 HIGH h3 before 2.0.1-rc.18 Denial of Service via Unbounded Chunked Cookie
CVE-2026-86251 5.9 MEDIUM h3 before 1.15.9 Path Traversal via Double Decoding
CVE-2026-86205 5.4 MEDIUM h3 before 2.0.1-rc.18 Open Redirect via redirectBack()
CVE-2026-86252 5.3 MEDIUM h3 before 1.15.9 SSE Event Injection via Carriage Return

IV. Related Vulnerabilities

Same product: h3
Same vendor: h3js
Same weakness: CWE-22

V. Comments for CVE-2026-86253

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