Hi,

The following vulnerability was published for perl.

It's fixed in sid + forky with Perl 5.42, but still presumably applies
to trixie and older. So filing a bug to track the issue.

The issue is already in the security tracker [1]. Salvatore & co: could
you please add a reference to this bug.

I expect this is suitable for a trixie point release once I get that
far with my TODO list.

CVE-2026-19487 [2]

  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

  Description
  -----------
  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.


[1] https://security-tracker.debian.org/tracker/CVE-2026-19487

[2] https://lists.security.metacpan.org/cve-announce/msg/42658992/