Critical
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
- 1.27-2build2, 1.29-1, 1.29-1build1, 1.29-1build3, 1.29-1ubuntu0.16.04.1~esm1, 1.29-1ubuntu0.18.04.1~esm1, 1.31-1, 1.31-1build1, 1.31-1ubuntu0.1~esm1, 1.34-1build1, 1.34-1build2, 1.34-1ubuntu0.1~esm1, 1.34-2, 1.34-2build1, 1.34-2build2, 1.34-2build3, 1.34-2ubuntu0.24.04.1~esm1, 1.34-3, 1.34-4, 1.36-1, 1.36-3, 1.47-1, 1.47-1build1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-57075
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:47 UTC · Revision 1
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:UBUNTU-CVE-2026-57075
libyaml-syck-perl
Fixed versions: Not specified
libyaml-syck-perl
Fixed versions: Not specified
libyaml-syck-perl
Fixed versions: Not specified
libyaml-syck-perl
Fixed versions: Not specified
libyaml-syck-perl
Fixed versions: Not specified
libyaml-syck-perl
Fixed versions: Not specified
libyaml-syck-perl
Fixed versions: Not specified
Complete source record
{
"id": "076fefcbea013db17f4bedd2f1b7b398ca58da7da538278dfe141f055bfeccb6",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-57075",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-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:UBUNTU-CVE-2026-57075",
"products": [
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.27-2build2",
"evidence": "/affected/0/versions"
},
{
"value": "1.29-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.29-1build1",
"evidence": "/affected/0/versions"
},
{
"value": "1.29-1ubuntu0.16.04.1~esm1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
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"affected_versions": [
{
"value": "1.29-1build3",
"evidence": "/affected/1/versions"
},
{
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"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.31-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.31-1build1",
"evidence": "/affected/2/versions"
},
{
"value": "1.31-1ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
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"evidence": "/affected/3/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "1.34-1build1",
"evidence": "/affected/3/versions"
},
{
"value": "1.34-1build2",
"evidence": "/affected/3/versions"
},
{
"value": "1.34-1ubuntu0.1~esm1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.34-2",
"evidence": "/affected/4/versions"
},
{
"value": "1.34-2build1",
"evidence": "/affected/4/versions"
},
{
"value": "1.34-2build2",
"evidence": "/affected/4/versions"
},
{
"value": "1.34-2build3",
"evidence": "/affected/4/versions"
},
{
"value": "1.34-2ubuntu0.24.04.1~esm1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.36-1",
"evidence": "/affected/5/versions"
},
{
"value": "1.36-3",
"evidence": "/affected/5/versions"
},
{
"value": "1.47-1",
"evidence": "/affected/5/versions"
},
{
"value": "1.47-1build1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "libyaml-syck-perl",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.34-3",
"evidence": "/affected/6/versions"
},
{
"value": "1.34-4",
"evidence": "/affected/6/versions"
},
{
"value": "1.36-1",
"evidence": "/affected/6/versions"
}
]
}
],
"severity": "critical",
"structured": {
"id": "UBUNTU-CVE-2026-57075",
"aliases": [
"UBUNTU-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"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"versions": [
"1.27-2build2",
"1.29-1",
"1.29-1build1",
"1.29-1ubuntu0.16.04.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-57075.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libyaml-syck-perl",
"binary_version": "1.29-1ubuntu0.16.04.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"1.29-1build3",
"1.29-1ubuntu0.18.04.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-57075.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libyaml-syck-perl",
"binary_version": "1.29-1ubuntu0.18.04.1~esm1"
}
]
}
},
{
"ranges": [
{
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],
"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"1.31-1",
"1.31-1build1",
"1.31-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-57075.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libyaml-syck-perl",
"binary_version": "1.31-1ubuntu0.1~esm1"
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"package": {
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"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fjammy",
"ecosystem": "Ubuntu:Pro:22.04:LTS"
},
"versions": [
"1.34-1build1",
"1.34-1build2",
"1.34-1ubuntu0.1~esm1"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
"binary_name": "libyaml-syck-perl",
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},
{
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"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=esm-apps%2Fnoble",
"ecosystem": "Ubuntu:Pro:24.04:LTS"
},
"versions": [
"1.34-2",
"1.34-2build1",
"1.34-2build2",
"1.34-2build3",
"1.34-2ubuntu0.24.04.1~esm1"
],
"database_specific": {
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},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libyaml-syck-perl",
"binary_version": "1.34-2ubuntu0.24.04.1~esm1"
}
]
}
},
{
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"package": {
"name": "libyaml-syck-perl",
"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
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"1.36-3",
"1.47-1",
"1.47-1build1"
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},
"ecosystem_specific": {
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{
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"package": {
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"purl": "pkg:deb/ubuntu/libyaml-syck-perl?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.34-3",
"1.34-4",
"1.36-1"
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"database_specific": {
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},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "1.36-1"
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]
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}
],
"modified": "2026-10-17T12:59:11.952351207Z",
"provider": "osv",
"upstream": [
"CVE-2026-57075"
],
"references": [
"https://ubuntu.com/security/CVE-2026-57075",
"https://www.cve.org/CVERecord?id=CVE-2026-57075",
"https://www.openwall.com/lists/oss-security/2026/07/17/2",
"https://github.com/toddr/YAML-Syck/commit/44c90a109ec3215ee7ce747bd11209835e123d8b.patch",
"https://metacpan.org/release/TODDR/YAML-Syck-1.47/changes"
]
},
"related_cves": [
{
"value": "CVE-2026-57075",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359418,
"published_at": "2026-07-16T22:17:00+00:00"
}