{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-33490", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-20T16:16:48.971Z", "datePublished": "2026-03-26T17:19:15.956Z", "dateUpdated": "2026-03-26T18:23:39.653Z"}, "containers": {"cna": {"title": "h3: Missing Path Segment Boundary Check in `mount()` Causes Middleware Execution on Unrelated Prefix-Matching Routes", "problemTypes": [{"descriptions": [{"cweId": "CWE-706", "lang": "en", "description": "CWE-706: Use of Incorrectly-Resolved Name or Reference", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 3.7, "baseSeverity": "LOW", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/h3js/h3/security/advisories/GHSA-2j6q-whv2-gh6w", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/h3js/h3/security/advisories/GHSA-2j6q-whv2-gh6w"}], "affected": [{"vendor": "h3js", "product": "h3", "versions": [{"version": ">= 2.0.1-alpha.0, < 2.0.1-rc.17", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-03-26T17:19:15.956Z"}, "descriptions": [{"lang": "en", "value": "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."}], "source": {"advisory": "GHSA-2j6q-whv2-gh6w", "discovery": "UNKNOWN"}}, "adp": [{"references": [{"url": "https://github.com/h3js/h3/security/advisories/GHSA-2j6q-whv2-gh6w", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-03-26T17:46:14.997707Z", "id": "CVE-2026-33490", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-26T18:23:39.653Z"}}]}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-33490", "lastModified": "2026-03-26T18:16:30.237", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 3.7, "baseSeverity": "LOW", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 1.4, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-03-26T18:16:30.237", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/h3js/h3/security/advisories/GHSA-2j6q-whv2-gh6w"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-706"}], "source": "security-advisories@github.com", "type": "Primary"}]}

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