{"api_version":"1","generated_at":"2026-09-01T09:18:52+00:00","cve":"CVE-2026-19953","urls":{"html":"https://cve.report/CVE-2026-19953","api":"https://cve.report/api/cve/CVE-2026-19953.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-19953","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-19953"},"summary":{"title":"URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep","description":"URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep.\n\nnameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. 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IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label.\n\nAny caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.","Type":"Description","Title":"URI versions before 5.36 for Perl encode non-NFC host names to n"}]}}}