libyaml-syck-perl — security advisory
YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec. The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path. Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.
- 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, 1.36-3
- Fixed versions
- 1.34-2+deb12u3, 1.34-2+deb13u3, 1.47-1
- CVEs
- CVE-2026-57075
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:52 UTC · Revision 2
Source evidence
YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec. The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path. Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.
osv:DEBIAN-CVE-2026-57075
libyaml-syck-perl
Fixed versions: 1.34-2+deb12u3
libyaml-syck-perl
Fixed versions: 1.34-2+deb13u3
libyaml-syck-perl
Fixed versions: 1.47-1
Complete source record
{
"id": "9a27b96fad23d2623aeb684415677fde3fd0e42061a4f22c0aeabe8e5ffb45a3",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-57075",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-57075",
"summary": "YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via a signed-char lookup-table index in syck_base64dec. The base64 decoder in the bundled libsyck indexes the 256-entry static table b64_xtable with a signed char, so any !!binary byte >= 0x80 sign-extends to a negative index and reads before the table. The decoder receives the raw bytes of any !!binary node, a standard YAML type not gated by $LoadBlessed or $LoadCode, so it is reached on the default Load path. Any caller that runs Load or LoadFile on an untrusted document containing a !!binary scalar with a high-bit byte triggers the read, and the value read can surface in the decoded result.",
"evidence": "osv:DEBIAN-CVE-2026-57075",
"products": [
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.34-2+deb12u3",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "1.34-2",
"evidence": "/affected/0/versions"
},
{
"value": "1.34-2+deb12u1",
"evidence": "/affected/0/versions"
},
{
"value": "1.34-2+deb12u2",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.34-2+deb13u3",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
"value": "1.34-2",
"evidence": "/affected/1/versions"
},
{
"value": "1.34-2+deb13u1",
"evidence": "/affected/1/versions"
},
{
"value": "1.34-2+deb13u2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.47-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "1.34-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.34-3",
"evidence": "/affected/2/versions"
},
{
"value": "1.34-4",
"evidence": "/affected/2/versions"
},
{
"value": "1.36-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.36-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.36-3",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "critical",
"structured": {
"id": "DEBIAN-CVE-2026-57075",
"aliases": [
"DEBIAN-CVE-2026-57075"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.34-2+deb12u3"
}
]
}
],
"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/debian/libyaml-syck-perl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"1.34-2",
"1.34-2+deb12u1",
"1.34-2+deb12u2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-57075.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.34-2+deb13u3"
}
]
}
],
"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-2026-57075.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.47-1"
}
]
}
],
"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/debian/libyaml-syck-perl?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"1.34-2",
"1.34-3",
"1.34-4",
"1.36-1",
"1.36-2",
"1.36-3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-57075.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-25T09:47:36.936299517Z",
"provider": "osv",
"upstream": [
"CVE-2026-57075"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-57075"
]
},
"related_cves": [
{
"value": "CVE-2026-57075",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 445156,
"published_at": "2026-07-16T22:17:43.447+00:00"
}