{"id":"AZL-98562","summary":"CVE-2026-19953 affecting package perl-URI 5.21-2","details":"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. 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.","modified":"2026-09-04T05:27:10Z","published":"2026-08-31T18:17:14Z","upstream":["CVE-2026-19953"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19953"}],"affected":[{"package":{"name":"perl-URI","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/perl-URI"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"5.21-2"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-98562.json"}}],"schema_version":"1.9.0"}