DEBIAN-CVE-2026-19487
Perl versions from 5.9.4 before 5.41.9 produce incorrect regular expression match results when a stale failure flag ends the Aho-Corasick prescan early in S_find_byclass. The prescan walks the subject for positions where the full pattern could match, and the engine tries it from the leftmost one recorded. A failing transition sets the failed flag, and a later successful transition does not clear it, so the prescan reads the stale flag as a failure and stops before it can record a candidate that starts earlier. It takes a subject where one candidate is recorded and a later character then forces a fallback through a fail link that succeeds. Example: "ABCDE" =~ m/ABCF|BCDE|C/; # matches C at offset 2, not BCDE "ABCDE" =~ m/ABCF|BCDE|C(G)/; # no match, BCDE missed An alternation like this can miss input it should match, or match it on the wrong branch, so an access or filtering decision made from the result can be wrong.
DEBIAN-CVE-2026-19487
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:DEBIAN-CVE-2026-19487
perl
Source reference: /affected/0/package/name
- Affected versions
- 5.36.0-7
Source reference:
/affected/0/versions5.36.0-7+deb12u1Source reference:
/affected/0/versions5.36.0-7+deb12u2Source reference:
/affected/0/versions5.36.0-7+deb12u3Source reference:
/affected/0/versions - Fixed versions
- 5.36.0-7+deb12u4
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
perl
Source reference: /affected/1/package/name
- Affected versions
- 5.40.1-6
Source reference:
/affected/1/versions - Fixed versions
- 5.40.1-6+deb13u1
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
perl
Source reference: /affected/2/package/name
- Affected versions
- 5.40.1-6
Source reference:
/affected/2/versions5.40.1-7Source reference:
/affected/2/versions5.40.1-8Source reference:
/affected/2/versions5.42.0-1Source reference:
/affected/2/versions5.42.0-2Source reference:
/affected/2/versions5.42.0-3Source reference:
/affected/2/versions5.42.2-1Source reference:
/affected/2/versions5.42.2-2Source reference:
/affected/2/versions - Fixed versions
- 5.42.2-3
Source reference:
/affected/2/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "5.36.0-7+deb12u4"
}
]
}
],
"package": {
"name": "perl",
"purl": "pkg:deb/debian/perl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"5.36.0-7",
"5.36.0-7+deb12u1",
"5.36.0-7+deb12u2",
"5.36.0-7+deb12u3"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-19487.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "5.40.1-6+deb13u1"
}
]
}
],
"package": {
"name": "perl",
"purl": "pkg:deb/debian/perl?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"5.40.1-6"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-19487.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "5.42.2-3"
}
]
}
],
"package": {
"name": "perl",
"purl": "pkg:deb/debian/perl?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"5.40.1-6",
"5.40.1-7",
"5.40.1-8",
"5.42.0-1",
"5.42.0-2",
"5.42.0-3",
"5.42.2-1",
"5.42.2-2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-19487.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]- Related CVEs
- CVE-2026-19487
Source reference:
/upstream
Publisher severity
medium
Source reference: /severity/0/score
- Event
- #85807 · Revision 1
- Added to Heist Feed
- Publisher date