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MediumFix available

DEBIAN-CVE-2026-19487

Type: advisorySource: OSV1 source record

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.

Announced Source revision 1
Original source ↗

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/versions

5.36.0-7+deb12u1

Source reference: /affected/0/versions

5.36.0-7+deb12u2

Source reference: /affected/0/versions

5.36.0-7+deb12u3

Source 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/versions

5.40.1-7

Source reference: /affected/2/versions

5.40.1-8

Source reference: /affected/2/versions

5.42.0-1

Source reference: /affected/2/versions

5.42.0-2

Source reference: /affected/2/versions

5.42.0-3

Source reference: /affected/2/versions

5.42.2-1

Source reference: /affected/2/versions

5.42.2-2

Source 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
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