High
libnet-idn-encode-perl — security advisory
Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode. The XS backend inserts each decoded code point into a UTF-8 buffer and finds the insertion point by scanning that buffer from the start, one character at a time. The scan runs once per code point over the output built so far, so the cost is quadratic in the label length. The pure-Perl backend downgrades its input to bytes so that substr can index it directly, but takes its working copy before the downgrade, so when the input carries the UTF-8 flag every substr on the copy scans from the start, with the same quadratic cost. Nothing bounds the label length in the to-Unicode direction. The 63-byte DNS limit is checked only when converting to ASCII, so domain_to_unicode and uts46_to_unicode pass an attacker-supplied label of any length to the decoder.
- Products
- libnet-idn-encode-perl
- Affected versions
- 2.202-1, 2.300-1, 2.300-1build1, 2.400-1build1, 2.500-1, 2.500-1build1, 2.500-1build2, 2.500-2, 2.500-2build1, 2.500-3, 2.500-3build1, 2.500-3build2, 2.500-5, 2.500-5build1, 2.500-5build2
- Fixed versions
- Not specified
- CVEs
- CVE-2026-87079
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:24 UTC · Revision 1
Source evidence
Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode. The XS backend inserts each decoded code point into a UTF-8 buffer and finds the insertion point by scanning that buffer from the start, one character at a time. The scan runs once per code point over the output built so far, so the cost is quadratic in the label length. The pure-Perl backend downgrades its input to bytes so that substr can index it directly, but takes its working copy before the downgrade, so when the input carries the UTF-8 flag every substr on the copy scans from the start, with the same quadratic cost. Nothing bounds the label length in the to-Unicode direction. The 63-byte DNS limit is checked only when converting to ASCII, so domain_to_unicode and uts46_to_unicode pass an attacker-supplied label of any length to the decoder.
osv:UBUNTU-CVE-2026-87079
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
libnet-idn-encode-perl
Fixed versions: Not specified
Complete source record
{
"id": "3ca591575439a8badd5eefd9ea35bb161161c6c2d413f351e4b48b8edc657a7d",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-87079",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-87079",
"summary": "Net::IDN::Punycode versions before 2.590 for Perl allow CPU exhaustion via quadratic insertion cost when decoding a long label in decode_punycode. The XS backend inserts each decoded code point into a UTF-8 buffer and finds the insertion point by scanning that buffer from the start, one character at a time. The scan runs once per code point over the output built so far, so the cost is quadratic in the label length. The pure-Perl backend downgrades its input to bytes so that substr can index it directly, but takes its working copy before the downgrade, so when the input carries the UTF-8 flag every substr on the copy scans from the start, with the same quadratic cost. Nothing bounds the label length in the to-Unicode direction. The 63-byte DNS limit is checked only when converting to ASCII, so domain_to_unicode and uts46_to_unicode pass an attacker-supplied label of any length to the decoder.",
"evidence": "osv:UBUNTU-CVE-2026-87079",
"products": [
{
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"value": "libnet-idn-encode-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.202-1",
"evidence": "/affected/0/versions"
},
{
"value": "2.300-1",
"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
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{
"name": {
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"affected_versions": [
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"affected_versions": [
{
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{
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]
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{
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"affected_versions": [
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"evidence": "/affected/3/versions"
},
{
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"evidence": "/affected/3/versions"
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{
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{
"name": {
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"evidence": "/affected/4/package/name"
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"affected_versions": [
{
"value": "2.500-3",
"evidence": "/affected/4/versions"
},
{
"value": "2.500-3build1",
"evidence": "/affected/4/versions"
},
{
"value": "2.500-3build2",
"evidence": "/affected/4/versions"
},
{
"value": "2.500-5",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
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"evidence": "/affected/5/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
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"evidence": "/affected/5/versions"
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{
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},
{
"name": {
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"evidence": "/affected/6/package/name"
},
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"affected_versions": [
{
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"evidence": "/affected/6/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-87079",
"aliases": [
"UBUNTU-CVE-2026-87079"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libnet-idn-encode-perl",
"purl": "pkg:deb/ubuntu/libnet-idn-encode-perl?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"2.202-1",
"2.300-1",
"2.300-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-87079.json"
},
"ecosystem_specific": {
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{
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"binary_version": "2.300-1build1"
}
]
}
},
{
"ranges": [
{
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"events": [
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}
],
"package": {
"name": "libnet-idn-encode-perl",
"purl": "pkg:deb/ubuntu/libnet-idn-encode-perl?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"2.400-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-87079.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libnet-idn-encode-perl",
"binary_version": "2.400-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
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],
"package": {
"name": "libnet-idn-encode-perl",
"purl": "pkg:deb/ubuntu/libnet-idn-encode-perl?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"2.500-1",
"2.500-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-87079.json"
},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "2.500-1build1"
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"package": {
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"purl": "pkg:deb/ubuntu/libnet-idn-encode-perl?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"2.500-1build2",
"2.500-2",
"2.500-2build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-87079.json"
},
"ecosystem_specific": {
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"binary_name": "libnet-idn-encode-perl",
"binary_version": "2.500-2build1"
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{
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"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"2.500-3",
"2.500-3build1",
"2.500-3build2",
"2.500-5"
],
"database_specific": {
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},
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"purl": "pkg:deb/ubuntu/libnet-idn-encode-perl?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"2.500-5build1",
"2.500-5build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-87079.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libnet-idn-encode-perl",
"binary_version": "2.500-5build2"
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]
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},
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"package": {
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"purl": "pkg:deb/ubuntu/libnet-idn-encode-perl?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"2.500-5build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-87079.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libnet-idn-encode-perl",
"binary_version": "2.500-5build1"
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]
}
}
],
"modified": "2026-10-17T13:01:14.177189133Z",
"provider": "osv",
"upstream": [
"CVE-2026-87079"
],
"references": [
"https://ubuntu.com/security/CVE-2026-87079",
"https://www.cve.org/CVERecord?id=CVE-2026-87079",
"https://lists.security.metacpan.org/cve-announce/msg/43753023/",
"https://github.com/robrwo/Net-IDN-Encode/commit/00d723423b66810af26b88c552bedc61975b3078.patch",
"https://github.com/robrwo/Net-IDN-Encode/commit/447c6b38ef5d4570329fa4f78690f4e14e09ba0c.patch",
"https://metacpan.org/release/PJCJ/Net-IDN-Encode-2.590-TRIAL/changes"
]
},
"related_cves": [
{
"value": "CVE-2026-87079",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 361333,
"published_at": "2026-09-22T08:16:00+00:00"
}