CVE-2026-33490 (GCVE-0-2026-33490)

Vulnerability from cvelistv5 – Published: 2026-03-26 17:19 – Updated: 2026-03-26 18:23
VLAI
Title
h3: Missing Path Segment Boundary Check in `mount()` Causes Middleware Execution on Unrelated Prefix-Matching Routes
Summary
H3 is a minimal H(TTP) framework. In versions 2.0.0-0 through 2.0.1-rc.16, the `mount()` method in h3 uses a simple `startsWith()` check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment boundary (i.e., that the next character after the base is `/` or end-of-string), middleware registered on a mount like `/admin` will also execute for unrelated routes such as `/admin-public`, `/administrator`, or `/adminstuff`. This allows an attacker to trigger context-setting middleware on paths it was never intended to cover, potentially polluting request context with unintended privilege flags. Version 2.0.2-rc.17 contains a patch.
Severity
3.7 (Low)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-26 17:46 UTC
CWE
  • CWE-706 - Use of Incorrectly-Resolved Name or Reference
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7831 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
h3js h3 Affected: >= 2.0.1-alpha.0, < 2.0.1-rc.17
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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