{"api_version":"1","generated_at":"2026-05-29T16:24:39+00:00","cve":"CVE-2026-39821","urls":{"html":"https://cve.report/CVE-2026-39821","api":"https://cve.report/api/cve/CVE-2026-39821.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-39821","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-39821"},"summary":{"title":"Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna","description":"The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode(\"xn--example-.com\") incorrectly returns the name \"example.com\" rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject \"example.com\" but permit \"xn--example-.com\". 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For example, ToUnicode(\"xn--example-.com\") incorrectly returns the name \"example.com\" rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject \"example.com\" but permit \"xn--example-.com\". If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name \"example.com\".","Type":"Description","Title":"Invoking failure to reject ASCII-only Punycode-encoded labels in"}]}}}