liburi-perl — security advisory
URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep. nameprep 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. Any 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.
- Products
- liburi-perl
- Affected versions
- 1.60-1, 1.69-1, 1.71-1, 1.72-1, 1.72-2, 1.73-1, 1.76-1, 1.76-2, 5.08-1, 5.10-1, 5.19-2, 5.21-1, 5.25-1, 5.27-1, 5.30-1, 5.34-2build1, 5.35-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-19953
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:42 UTC · Revision 1
Source evidence
URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep. nameprep 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. Any 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.
osv:UBUNTU-CVE-2026-19953
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
liburi-perl
Fixed versions: Not specified
Complete source record
{
"id": "bef68ae85a872326365aeef52bdfbff7e3d138021b3e41e79a632af8c1f88ddf",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-19953",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-19953",
"summary": "URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep. nameprep 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. Any 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.",
"evidence": "osv:UBUNTU-CVE-2026-19953",
"products": [
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.60-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.69-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.71-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.72-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.72-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.73-1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.76-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.76-2",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.08-1",
"evidence": "/affected/4/versions"
},
{
"value": "5.10-1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.19-2",
"evidence": "/affected/5/versions"
},
{
"value": "5.21-1",
"evidence": "/affected/5/versions"
},
{
"value": "5.25-1",
"evidence": "/affected/5/versions"
},
{
"value": "5.27-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.34-2build1",
"evidence": "/affected/6/versions"
},
{
"value": "5.35-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "liburi-perl",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.30-1",
"evidence": "/affected/7/versions"
},
{
"value": "5.34-2build1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-19953",
"aliases": [
"UBUNTU-CVE-2026-19953"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=trusty",
"ecosystem": "Ubuntu:14.04:LTS"
},
"versions": [
"1.60-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "1.60-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"1.69-1",
"1.71-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "1.71-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"1.72-1",
"1.72-2",
"1.73-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "1.73-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"1.76-1",
"1.76-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "1.76-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"5.08-1",
"5.10-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "5.10-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"5.19-2",
"5.21-1",
"5.25-1",
"5.27-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "5.27-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"5.34-2build1",
"5.35-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "5.35-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "liburi-perl",
"purl": "pkg:deb/ubuntu/liburi-perl?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"5.30-1",
"5.34-2build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-19953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "liburi-perl",
"binary_version": "5.34-2build1"
}
]
}
}
],
"modified": "2026-10-17T12:58:47.066451288Z",
"provider": "osv",
"upstream": [
"CVE-2026-19953"
],
"references": [
"https://ubuntu.com/security/CVE-2026-19953",
"https://www.cve.org/CVERecord?id=CVE-2026-19953"
]
},
"related_cves": [
{
"value": "CVE-2026-19953",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359047,
"published_at": "2026-08-31T18:17:00+00:00"
}