libyaml-syck-perl — security advisory
YAML::Syck versions before 1.38 for Perl has an out-of-bounds read. The base60 (sexagesimal) parsing code in perl_syck.h has a buffer underflow bug in both int#base60 and float#base60 handlers. When processing the leftmost segment of a colon-separated value (e.g., the 1 in 1:30:45), the inner while loop can decrement a pointer past the start of the string buffer: while ( colon >= ptr && *colon != ':' ) { colon--; } if ( *colon == ':' ) *colon = '\0'; // colon may be ptr-1 here When no colon is found (final/leftmost segment), colon becomes ptr-1, and the subsequent *colon dereference reads one byte before the allocated buffer.
- Products
- libyaml-syck-perl
- Affected versions
- 1.34-2, 1.34-2+deb12u1, 1.34-2+deb12u2, 1.34-2+deb13u1, 1.34-2+deb13u2, 1.34-3, 1.34-4, 1.36-1, 1.36-2
- Fixed versions
- 1.34-2+deb12u3, 1.34-2+deb13u3, 1.36-3
- CVEs
- CVE-2026-5089
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 17:52 UTC · Revision 2
Source evidence
YAML::Syck versions before 1.38 for Perl has an out-of-bounds read. The base60 (sexagesimal) parsing code in perl_syck.h has a buffer underflow bug in both int#base60 and float#base60 handlers. When processing the leftmost segment of a colon-separated value (e.g., the 1 in 1:30:45), the inner while loop can decrement a pointer past the start of the string buffer: while ( colon >= ptr && *colon != ':' ) { colon--; } if ( *colon == ':' ) *colon = '\0'; // colon may be ptr-1 here When no colon is found (final/leftmost segment), colon becomes ptr-1, and the subsequent *colon dereference reads one byte before the allocated buffer.
osv:DEBIAN-CVE-2026-5089
libyaml-syck-perl
Fixed versions: 1.34-2+deb12u3
libyaml-syck-perl
Fixed versions: 1.34-2+deb13u3
libyaml-syck-perl
Fixed versions: 1.36-3
Complete source record
{
"id": "8bdaccfca64e4ec10386d4ecf38e414b0889c4752ea3f28f912c00bbf2cdbc78",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-5089",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-5089",
"summary": "YAML::Syck versions before 1.38 for Perl has an out-of-bounds read. The base60 (sexagesimal) parsing code in perl_syck.h has a buffer underflow bug in both int#base60 and float#base60 handlers. When processing the leftmost segment of a colon-separated value (e.g., the 1 in 1:30:45), the inner while loop can decrement a pointer past the start of the string buffer: while ( colon >= ptr && *colon != ':' ) { colon--; } if ( *colon == ':' ) *colon = '\\0'; // colon may be ptr-1 here When no colon is found (final/leftmost segment), colon becomes ptr-1, and the subsequent *colon dereference reads one byte before the allocated buffer.",
"evidence": "osv:DEBIAN-CVE-2026-5089",
"products": [
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
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"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
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"value": "1.34-2",
"evidence": "/affected/0/versions"
},
{
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"evidence": "/affected/0/versions"
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{
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"evidence": "/affected/0/versions"
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},
{
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},
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{
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{
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"evidence": "/affected/2/versions"
},
{
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"evidence": "/affected/2/versions"
},
{
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"evidence": "/affected/2/versions"
},
{
"value": "1.36-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.36-2",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2026-5089",
"aliases": [
"DEBIAN-CVE-2026-5089"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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},
{
"fixed": "1.34-2+deb12u3"
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]
}
],
"package": {
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"purl": "pkg:deb/debian/libyaml-syck-perl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
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"1.34-2+deb12u1",
"1.34-2+deb12u2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-5089.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
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"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
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{
"fixed": "1.34-2+deb13u3"
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],
"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/debian/libyaml-syck-perl?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"1.34-2",
"1.34-2+deb13u1",
"1.34-2+deb13u2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-5089.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
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},
{
"ranges": [
{
"type": "ECOSYSTEM",
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"package": {
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"purl": "pkg:deb/debian/libyaml-syck-perl?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
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"1.34-3",
"1.34-4",
"1.36-1",
"1.36-2"
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"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-5089.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-27T09:47:43.994250374Z",
"provider": "osv",
"upstream": [
"CVE-2026-5089"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-5089"
]
},
"related_cves": [
{
"value": "CVE-2026-5089",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 461399,
"published_at": "2026-05-12T17:16:21.72+00:00"
}