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perl-5.43.9
⭐ Starred 2013 / Tie::Memoize
Security Advisories (3)
CVE-2026-13221 (2026-07-13)

Perl versions through 5.43.9 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk. When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie's match decision table is truncated with no warning or error. A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.

CVE-2026-57432 (2026-07-13)

Perl versions through 5.43.10 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack. S_measure_struct adds each item's size times its repeat count to a running total with no overflow check, so a large repeat count in a pack or unpack template wraps the signed SSize_t total negative. The @, X, and x position codes then guard their moves with a signed length comparison that passes when the length is negative, advancing the buffer pointer out of bounds. A template derived from untrusted input can read heap memory past the buffer and return it to the caller.

CVE-2026-8376 (2026-05-25)

Perl versions through 5.43.10 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds. Perl_study_chunk in regcomp_study.c checked the size of the joined substring buffer in characters rather than bytes. For a quantified fixed substring with a large minimum count, the byte length mincount * l could overflow SSize_t, producing an undersized SvGROW allocation; the subsequent copy writes past the end of the buffer. A caller that compiles an attacker-controlled regular expression on a 32-bit perl build triggers a heap buffer overflow at compile time.

NAME

Tie::Memoize - add data to hash when needed

SYNOPSIS

require Tie::Memoize;
tie %hash, 'Tie::Memoize',
    \&fetch,			# The rest is optional
    $DATA, \&exists,
    {%ini_value}, {%ini_existence};

DESCRIPTION

This package allows a tied hash to autoload its values on the first access, and to use the cached value on the following accesses.

Only read-accesses (via fetching the value or exists) result in calls to the functions; the modify-accesses are performed as on a normal hash.

The required arguments during tie are the hash, the package, and the reference to the FETCHing function. The optional arguments are an arbitrary scalar $data, the reference to the EXISTS function, and initial values of the hash and of the existence cache.

Both the FETCHing function and the EXISTS functions have the same signature: the arguments are $key, $data; $data is the same value as given as argument during tie()ing. Both functions should return an empty list if the value does not exist. If EXISTS function is different from the FETCHing function, it should return a TRUE value on success. The FETCHing function should return the intended value if the key is valid.

Inheriting from Tie::Memoize

The structure of the tied() data is an array reference with elements

0:  cache of known values
1:  cache of known existence of keys
2:  FETCH  function
3:  EXISTS function
4:  $data

The rest is for internal usage of this package. In particular, if TIEHASH is overwritten, it should call SUPER::TIEHASH.

EXAMPLE

sub slurp {
  my ($key, $dir) = shift;
  open my $h, '<', "$dir/$key" or return;
  local $/; <$h>			# slurp it all
}
sub exists { my ($key, $dir) = shift; return -f "$dir/$key" }

tie %hash, 'Tie::Memoize', \&slurp, $directory, \&exists,
    { fake_file1 => $content1, fake_file2 => $content2 },
    { pretend_does_not_exists => 0, known_to_exist => 1 };

This example treats the slightly modified contents of $directory as a hash. The modifications are that the keys fake_file1 and fake_file2 fetch values $content1 and $content2, and pretend_does_not_exists will never be accessed. Additionally, the existence of known_to_exist is never checked (so if it does not exists when its content is needed, the user of %hash may be confused).

BUGS

FIRSTKEY and NEXTKEY methods go through the keys which were already read, not all the possible keys of the hash.

AUTHOR

Ilya Zakharevich mailto:perl-module-hash-memoize@ilyaz.org.