/ 
perl-5.35.8
⭐ Starred 2013 / builtin
Security Advisories (7)
CVE-2024-56406 (2025-04-13)

A heap buffer overflow vulnerability was discovered in Perl. Release branches 5.34, 5.36, 5.38 and 5.40 are affected, including development versions from 5.33.1 through 5.41.10. When there are non-ASCII bytes in the left-hand-side of the `tr` operator, `S_do_trans_invmap` can overflow the destination pointer `d`.    $ perl -e '$_ = "\x{FF}" x 1000000; tr/\xFF/\x{100}/;'    Segmentation fault (core dumped) It is believed that this vulnerability can enable Denial of Service and possibly Code Execution attacks on platforms that lack sufficient defenses.

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-2026-15534 (2026-08-09)

Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.

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.

CVE-2025-40909 (2025-05-30)

Perl threads have a working directory race condition where file operations may target unintended paths. If a directory handle is open at thread creation, the process-wide current working directory is temporarily changed in order to clone that handle for the new thread, which is visible from any third (or more) thread already running. This may lead to unintended operations such as loading code or accessing files from unexpected locations, which a local attacker may be able to exploit. The bug was introduced in commit 11a11ecf4bea72b17d250cfb43c897be1341861e and released in Perl version 5.13.6

CVE-2026-4176 (2026-03-29)

Perl versions from 5.9.4 before 5.40.4-RC1, from 5.41.0 before 5.42.2-RC1, from 5.43.0 before 5.43.9 contain a vulnerable version of Compress::Raw::Zlib. Compress::Raw::Zlib is included in the Perl package as a dual-life core module, and is vulnerable to CVE-2026-3381 due to a vendored version of zlib which has several vulnerabilities, including CVE-2026-27171. The bundled Compress::Raw::Zlib was updated to version 2.221 in Perl blead commit c75ae9cc164205e1b6d6dbd57bd2c65c8593fe94.

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.

NAME

builtin - Perl pragma to import built-in utility functions

SYNOPSIS

use builtin qw(
    true false isbool
    weaken unweaken isweak
    blessed refaddr reftype
);

DESCRIPTION

Perl provides several utility functions in the builtin package. These are plain functions, and look and behave just like regular user-defined functions do. They do not provide new syntax or require special parsing. These functions are always present in the interpreter and can be called at any time by their fully-qualified names. By default they are not available as short names, but can be requested for convenience.

Individual named functions can be imported by listing them as import parameters on the use statement for this pragma.

The overall builtin mechanism, as well as every individual function it provides, are currently experimental.

Lexical Import

This pragma module creates lexical aliases in the currently-compiling scope to these builtin functions. This is similar to the lexical effect of other pragmas such as strict and feature.

sub classify
{
    my $sv = shift;

    use builtin 'isbool';
    return isbool($sv) ? "boolean" : "not a boolean";
}

# the isbool() function is no longer visible here
# but may still be called by builtin::isbool()

Because these functions are imported lexically, rather than by package symbols, the user does not need to take any special measures to ensure they don't accidentally appear as object methods from a class.

package An::Object::Class {
    use builtin 'true', 'false';
    ...
}

# does not appear as a method
An::Object::Class->true;

# Can't locate object method "true" via package "An::Object::Class"
#   at ...

FUNCTIONS

true

$val = true;

Returns the boolean truth value. While any scalar value can be tested for truth and most defined, non-empty and non-zero values are considered "true" by perl, this one is special in that "isbool" considers it to be a distinguished boolean value.

This gives an equivalent value to expressions like !!1 or !0.

false

$val = false;

Returns the boolean fiction value. While any non-true scalar value is considered "false" by perl, this one is special in that "isbool" considers it to be a distinguished boolean value.

This gives an equivalent value to expressions like !!0 or !1.

isbool

$bool = isbool($val);

Returns true when given a distinguished boolean value, or false if not. A distinguished boolean value is the result of any boolean-returning builtin function (such as true or isbool itself), boolean-returning operator (such as the eq or == comparison tests or the ! negation operator), or any variable containing one of these results.

weaken

weaken($ref);

Weakens a reference. A weakened reference does not contribute to the reference count of its referent. If only weakened references to a referent remain, it will be disposed of, and all remaining weak references to it will have their value set to undef.

unweaken

unweaken($ref);

Strengthens a reference, undoing the effects of a previous call to "weaken".

isweak

$bool = isweak($ref);

Returns true when given a weakened reference, or false if not a reference or not weak.

blessed

$str = blessed($ref);

Returns the package name for an object reference, or undef for a non-reference or reference that is not an object.

refaddr

$num = refaddr($ref);

Returns the memory address for a reference, or undef for a non-reference. This value is not likely to be very useful for pure Perl code, but is handy as a means to test for referential identity or uniqueness.

reftype

$str = reftype($ref);

Returns the basic container type of the referent of a reference, or undef for a non-reference. This is returned as a string in all-capitals, such as ARRAY for array references, or HASH for hash references.

SEE ALSO

perlop, perlfunc, Scalar::Util