CriticalFix available
libmojolicious-perl — security advisory
Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BREACH compression oracle. _csrf_token generates and caches one token per session and returns the same value on every call, and _csrf_field places that value in a hidden `csrf_token` input. When a response carrying the token also echoes attacker-controlled input and is gzip-compressed, the chosen values and the resulting compressed lengths form a BREACH oracle. An attacker able to query it can recover the token and pass csrf_protect validation.
- Products
- libmojolicious-perl
- Affected versions
- 9.31+dfsg-1, 9.33+dfsg-1, 9.34+dfsg-1, 9.35+dfsg-1, 9.36+dfsg-1, 9.36+dfsg-1~bpo12+2, 9.37+dfsg-1, 9.37+dfsg-2, 9.37+dfsg-2~bpo12+1, 9.38+dfsg-1, 9.39+dfsg-1, 9.42+dfsg-1, 9.42+dfsg-1~bpo13+2, 9.45+dfsg-1, 9.45+dfsg-2, 9.46+dfsg-1, 9.47+dfsg-1, 9.48+dfsg-1, 9.49+dfsg-1
- Fixed versions
- 9.48+dfsg-1
- CVEs
- CVE-2026-15747
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:56 UTC · Revision 2
Source evidence
Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BREACH compression oracle. _csrf_token generates and caches one token per session and returns the same value on every call, and _csrf_field places that value in a hidden `csrf_token` input. When a response carrying the token also echoes attacker-controlled input and is gzip-compressed, the chosen values and the resulting compressed lengths form a BREACH oracle. An attacker able to query it can recover the token and pass csrf_protect validation.
osv:DEBIAN-CVE-2026-15747
libmojolicious-perl
Fixed versions: Not specified
libmojolicious-perl
Fixed versions: Not specified
libmojolicious-perl
Fixed versions: 9.48+dfsg-1
Complete source record
{
"id": "468c3f1f85c229b16b7d05a57a9b058feea5551727f02a42ec5e6dc32ced71dc",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-15747",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-15747",
"summary": "Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BREACH compression oracle. _csrf_token generates and caches one token per session and returns the same value on every call, and _csrf_field places that value in a hidden `csrf_token` input. When a response carrying the token also echoes attacker-controlled input and is gzip-compressed, the chosen values and the resulting compressed lengths form a BREACH oracle. An attacker able to query it can recover the token and pass csrf_protect validation.",
"evidence": "osv:DEBIAN-CVE-2026-15747",
"products": [
{
"name": {
"value": "libmojolicious-perl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "9.31+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.33+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.34+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.35+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.36+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.36+dfsg-1~bpo12+2",
"evidence": "/affected/0/versions"
},
{
"value": "9.37+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.37+dfsg-2",
"evidence": "/affected/0/versions"
},
{
"value": "9.37+dfsg-2~bpo12+1",
"evidence": "/affected/0/versions"
},
{
"value": "9.38+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.39+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.42+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.42+dfsg-1~bpo13+2",
"evidence": "/affected/0/versions"
},
{
"value": "9.45+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.45+dfsg-2",
"evidence": "/affected/0/versions"
},
{
"value": "9.46+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.47+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.48+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "9.49+dfsg-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "libmojolicious-perl",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "9.39+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "9.42+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "9.42+dfsg-1~bpo13+2",
"evidence": "/affected/1/versions"
},
{
"value": "9.45+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "9.45+dfsg-2",
"evidence": "/affected/1/versions"
},
{
"value": "9.46+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "9.47+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "9.48+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "9.49+dfsg-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "libmojolicious-perl",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "9.48+dfsg-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "9.39+dfsg-1",
"evidence": "/affected/2/versions"
},
{
"value": "9.42+dfsg-1",
"evidence": "/affected/2/versions"
},
{
"value": "9.42+dfsg-1~bpo13+2",
"evidence": "/affected/2/versions"
},
{
"value": "9.45+dfsg-1",
"evidence": "/affected/2/versions"
},
{
"value": "9.45+dfsg-2",
"evidence": "/affected/2/versions"
},
{
"value": "9.46+dfsg-1",
"evidence": "/affected/2/versions"
},
{
"value": "9.47+dfsg-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "critical",
"structured": {
"id": "DEBIAN-CVE-2026-15747",
"aliases": [
"DEBIAN-CVE-2026-15747"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libmojolicious-perl",
"purl": "pkg:deb/debian/libmojolicious-perl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"9.31+dfsg-1",
"9.33+dfsg-1",
"9.34+dfsg-1",
"9.35+dfsg-1",
"9.36+dfsg-1",
"9.36+dfsg-1~bpo12+2",
"9.37+dfsg-1",
"9.37+dfsg-2",
"9.37+dfsg-2~bpo12+1",
"9.38+dfsg-1",
"9.39+dfsg-1",
"9.42+dfsg-1",
"9.42+dfsg-1~bpo13+2",
"9.45+dfsg-1",
"9.45+dfsg-2",
"9.46+dfsg-1",
"9.47+dfsg-1",
"9.48+dfsg-1",
"9.49+dfsg-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-15747.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libmojolicious-perl",
"purl": "pkg:deb/debian/libmojolicious-perl?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"9.39+dfsg-1",
"9.42+dfsg-1",
"9.42+dfsg-1~bpo13+2",
"9.45+dfsg-1",
"9.45+dfsg-2",
"9.46+dfsg-1",
"9.47+dfsg-1",
"9.48+dfsg-1",
"9.49+dfsg-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-15747.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "9.48+dfsg-1"
}
]
}
],
"package": {
"name": "libmojolicious-perl",
"purl": "pkg:deb/debian/libmojolicious-perl?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"9.39+dfsg-1",
"9.42+dfsg-1",
"9.42+dfsg-1~bpo13+2",
"9.45+dfsg-1",
"9.45+dfsg-2",
"9.46+dfsg-1",
"9.47+dfsg-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-15747.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-25T10:00:15.607497673Z",
"provider": "osv",
"upstream": [
"CVE-2026-15747"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-15747"
]
},
"related_cves": [
{
"value": "CVE-2026-15747",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 445348,
"published_at": "2026-07-14T18:17:12.587+00:00"
}