/ 
perl5.003_08
/ pod/perli18n.pod
Security Advisories (32)
CVE-1999-1386 (1999-12-31)

Perl 5.004_04 and earlier follows symbolic links when running with the -e option, which allows local users to overwrite arbitrary files via a symlink attack on the /tmp/perl-eaXXXXX file.

CVE-1999-0034 (1997-05-29)

Buffer overflow in suidperl (sperl), Perl 4.x and 5.x.

CVE-1999-0462 (1999-03-17)

suidperl in Linux Perl does not check the nosuid mount option on file systems, allowing local users to gain root access by placing a setuid script in a mountable file system, e.g. a CD-ROM or floppy disk.

CVE-2000-0703 (2000-10-20)

suidperl (aka sperl) does not properly cleanse the escape sequence "~!" before calling /bin/mail to send an error report, which allows local users to gain privileges by setting the "interactive" environmental variable and calling suidperl with a filename that contains the escape sequence.

CVE-2005-3962 (2005-12-01)

Integer overflow in the format string functionality (Perl_sv_vcatpvfn) in Perl 5.9.2 and 5.8.6 Perl allows attackers to overwrite arbitrary memory and possibly execute arbitrary code via format string specifiers with large values, which causes an integer wrap and leads to a buffer overflow, as demonstrated using format string vulnerabilities in Perl applications.

CVE-2010-1158 (2010-04-20)

Integer overflow in the regular expression engine in Perl 5.8.x allows context-dependent attackers to cause a denial of service (stack consumption and application crash) by matching a crafted regular expression against a long string.

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-2018-6913 (2018-04-17)

Heap-based buffer overflow in the pack function in Perl before 5.26.2 allows context-dependent attackers to execute arbitrary code via a large item count.

CVE-2011-2728 (2012-12-21)

The bsd_glob function in the File::Glob module for Perl before 5.14.2 allows context-dependent attackers to cause a denial of service (crash) via a glob expression with the GLOB_ALTDIRFUNC flag, which triggers an uninitialized pointer dereference.

CVE-2018-18314 (2018-12-07)

Perl before 5.26.3 has a buffer overflow via a crafted regular expression that triggers invalid write operations.

CVE-2018-18312 (2018-12-05)

Perl before 5.26.3 and 5.28.0 before 5.28.1 has a buffer overflow via a crafted regular expression that triggers invalid write operations.

CVE-2018-18311 (2018-12-07)

Perl before 5.26.3 and 5.28.x before 5.28.1 has a buffer overflow via a crafted regular expression that triggers invalid write operations.

CVE-2013-1667 (2013-03-14)

The rehash mechanism in Perl 5.8.2 through 5.16.x allows context-dependent attackers to cause a denial of service (memory consumption and crash) via a crafted hash key.

CVE-2010-4777 (2014-02-10)

The Perl_reg_numbered_buff_fetch function in Perl 5.10.0, 5.12.0, 5.14.0, and other versions, when running with debugging enabled, allows context-dependent attackers to cause a denial of service (assertion failure and application exit) via crafted input that is not properly handled when using certain regular expressions, as demonstrated by causing SpamAssassin and OCSInventory to crash.

CVE-2008-1927 (2008-04-24)

Double free vulnerability in Perl 5.8.8 allows context-dependent attackers to cause a denial of service (memory corruption and crash) via a crafted regular expression containing UTF8 characters. NOTE: this issue might only be present on certain operating systems.

CVE-2013-7422 (2015-08-16)

Integer underflow in regcomp.c in Perl before 5.20, as used in Apple OS X before 10.10.5 and other products, allows context-dependent attackers to execute arbitrary code or cause a denial of service (application crash) via a long digit string associated with an invalid backreference within a regular expression.

CVE-2023-47039 (2023-10-30)

Perl for Windows relies on the system path environment variable to find the shell (cmd.exe). When running an executable which uses Windows Perl interpreter, Perl attempts to find and execute cmd.exe within the operating system. However, due to path search order issues, Perl initially looks for cmd.exe in the current working directory. An attacker with limited privileges can exploit this behavior by placing cmd.exe in locations with weak permissions, such as C:\ProgramData. By doing so, when an administrator attempts to use this executable from these compromised locations, arbitrary code can be executed.

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.

CVE-2016-1238 (2016-08-02)

(1) cpan/Archive-Tar/bin/ptar, (2) cpan/Archive-Tar/bin/ptardiff, (3) cpan/Archive-Tar/bin/ptargrep, (4) cpan/CPAN/scripts/cpan, (5) cpan/Digest-SHA/shasum, (6) cpan/Encode/bin/enc2xs, (7) cpan/Encode/bin/encguess, (8) cpan/Encode/bin/piconv, (9) cpan/Encode/bin/ucmlint, (10) cpan/Encode/bin/unidump, (11) cpan/ExtUtils-MakeMaker/bin/instmodsh, (12) cpan/IO-Compress/bin/zipdetails, (13) cpan/JSON-PP/bin/json_pp, (14) cpan/Test-Harness/bin/prove, (15) dist/ExtUtils-ParseXS/lib/ExtUtils/xsubpp, (16) dist/Module-CoreList/corelist, (17) ext/Pod-Html/bin/pod2html, (18) utils/c2ph.PL, (19) utils/h2ph.PL, (20) utils/h2xs.PL, (21) utils/libnetcfg.PL, (22) utils/perlbug.PL, (23) utils/perldoc.PL, (24) utils/perlivp.PL, and (25) utils/splain.PL in Perl 5.x before 5.22.3-RC2 and 5.24 before 5.24.1-RC2 do not properly remove . (period) characters from the end of the includes directory array, which might allow local users to gain privileges via a Trojan horse module under the current working directory.

CVE-2020-12723 (2020-06-05)

regcomp.c in Perl before 5.30.3 allows a buffer overflow via a crafted regular expression because of recursive S_study_chunk calls.

CVE-2020-10878 (2020-06-05)

Perl before 5.30.3 has an integer overflow related to mishandling of a "PL_regkind[OP(n)] == NOTHING" situation. A crafted regular expression could lead to malformed bytecode with a possibility of instruction injection.

CVE-2020-10543 (2020-06-05)

Perl before 5.30.3 on 32-bit platforms allows a heap-based buffer overflow because nested regular expression quantifiers have an integer overflow.

CVE-2018-18313 (2018-12-07)

Perl before 5.26.3 has a buffer over-read via a crafted regular expression that triggers disclosure of sensitive information from process memory.

CVE-2015-8853 (2016-05-25)

The (1) S_reghop3, (2) S_reghop4, and (3) S_reghopmaybe3 functions in regexec.c in Perl before 5.24.0 allow context-dependent attackers to cause a denial of service (infinite loop) via crafted utf-8 data, as demonstrated by "a\x80."

CVE-2009-3626 (2009-10-29)

Perl 5.10.1 allows context-dependent attackers to cause a denial of service (application crash) via a UTF-8 character with a large, invalid codepoint, which is not properly handled during a regular-expression match.

CVE-2007-5116 (2007-11-07)

Buffer overflow in the polymorphic opcode support in the Regular Expression Engine (regcomp.c) in Perl 5.8 allows context-dependent attackers to execute arbitrary code by switching from byte to Unicode (UTF) characters in a regular expression.

CVE-2012-5195 (2012-12-18)

Heap-based buffer overflow in the Perl_repeatcpy function in util.c in Perl 5.12.x before 5.12.5, 5.14.x before 5.14.3, and 5.15.x before 15.15.5 allows context-dependent attackers to cause a denial of service (memory consumption and crash) or possibly execute arbitrary code via the 'x' string repeat operator.

CVE-2016-2381 (2016-04-08)

Perl might allow context-dependent attackers to bypass the taint protection mechanism in a child process via duplicate environment variables in envp.

CVE-2011-1487 (2011-04-11)

The (1) lc, (2) lcfirst, (3) uc, and (4) ucfirst functions in Perl 5.10.x, 5.11.x, and 5.12.x through 5.12.3, and 5.13.x through 5.13.11, do not apply the taint attribute to the return value upon processing tainted input, which might allow context-dependent attackers to bypass the taint protection mechanism via a crafted string.

CVE-2023-47100

In Perl before 5.38.2, S_parse_uniprop_string in regcomp.c can write to unallocated space because a property name associated with a \p{...} regular expression construct is mishandled. The earliest affected version is 5.30.0.

NAME

perl18n - Perl i18n (internalization)

DESCRIPTION

Perl supports the language-specific notions of data like "is this a letter" and "which letter comes first". These are very important issues especially for languages other than English -- but also for English: it would be very naïve indeed to think that A-Za-z defines all the letters.

Perl understands the language-specific data via the standardized (ISO C, XPG4, POSIX 1.c) method called "the locale system". The locale system is controlled per application using one function call and several environment variables.

USING LOCALES

If your operating system supports the locale system and you have installed the locale system and you have set your locale environment variables correctly (please see below) before running Perl, Perl will understand your data correctly according to your locale settings.

In runtime you can switch locales using the POSIX::setlocale().

# setlocale is the function call
# LC_CTYPE will be explained later

use POSIX qw(setlocale LC_CTYPE);

# query and save the old locale.
$old_locale = setlocale(LC_CTYPE);

setlocale(LC_CTYPE, "fr_CA.ISO8859-1");
# for LC_CTYPE now in locale "French, Canada, codeset ISO 8859-1"

setlocale(LC_CTYPE, "");
# for LC_CTYPE now in locale what the LC_ALL / LC_CTYPE / LANG define.
# see below for documentation about the LC_ALL / LC_CTYPE / LANG.

# restore the old locale
setlocale(LC_CTYPE, $old_locale);

The first argument of setlocale() is called the category and the second argument the locale. The category tells in what aspect of data processing we want to apply language-specific rules, the locale tells in what language-country/territory-codeset - but read on for the naming of the locales: not all systems name locales as in the example.

For further information about the categories, please consult your setlocale(3) manual. For the locales available in your system, also consult the setlocale(3) manual and see whether it leads you to the list of the available locales (search for the SEE ALSO section). If that fails, try out in command line the following commands:

locale -a
nlsinfo
ls /usr/lib/nls/loc
ls /usr/lib/locale
ls /usr/lib/nls

and see whether they list something resembling these

en_US.ISO8859-1		de_DE.ISO8859-1		ru_RU.ISO8859-5
en_US			de_DE			ru_RU
en			de			ru
english			german			russian
english.iso88591	german.iso88591		russian.iso88595

Sadly enough even if the calling interface has been standardized the names of the locales are not. The naming usually is language-country/territory-codeset but the latter parts may not be present. Two special locales are worth special mention:

"C"

and "POSIX"

Currently and effectively these are the same locale: the difference is mainly that the first one is defined by the C standard and the second one is defined by the POSIX standard. What they mean and define is the default locale in which every program does start in. The language is (American) English and the character codeset ASCII. NOTE: not all systems have the "POSIX" locale (not all systems are POSIX): use the "C" locale when you need the default locale.

Category LC_CTYPE: CHARACTER TYPES

Starting from Perl version 5.002 perl has obeyed the LC_CTYPE environment variable which controls application's notions on which characters are alphabetic characters. This affects in Perl the regular expression metanotation

\w

which stands for alphanumeric characters, that is, alphabetic and numeric characters (please consult perlre for more information about regular expressions). Thanks to the LC_CTYPE, depending on your locale settings, characters like Æ, É, ß, ø, can be understood as \w characters.

Category LC_COLLATE: COLLATION

Starting from Perl version 5.003_06 perl has obeyed the LC_COLLATE environment variable which controls application's notions on the collation (ordering) of the characters. B does in most Latin alphabets follow the A but where do the Á and Ä belong?

Here is a code snippet that will tell you what are the alphanumeric characters in the current locale, in the locale order:

perl -le 'print sort grep /\w/, map { chr() } 0..255'

As noted above, this will work only for Perl versions 5.003_06 and up.

NOTE: in the pre-5.003_06 Perl releases the per-locale collation was possible using the I18N::Collate library module. This is now mildly obsolete and to be avoided. The LC_COLLATE functionality is integrated into the Perl core language and one can use scalar data completely normally -- there is no need to juggle with the scalar references of I18N::Collate.

ENVIRONMENT

PERL_BADLANG

A string that controls whether Perl warns in its startup about failed locale settings. This can happen if the locale support in the operating system is lacking (broken) is some way. If this string has an integer value differing from zero, Perl will not complain. NOTE: this is just hiding the warning message: the message tells about some problem in your system's locale support and you should investigate what the problem is.

The following environment variables are not specific to Perl: they are part of the standardized (ISO C, XPG4, POSIX 1.c) setlocale method to control an application's opinion on data.

LC_ALL

LC_ALL is the "override-all" locale environment variable. If it is set, it overrides all the rest of the locale environment variables.

LC_CTYPE

LC_ALL controls the classification of characters, see above.

If this is unset and the LC_ALL is set, the LC_ALL is used as the LC_CTYPE. If both this and the LC_ALL are unset but the LANG is set, the LANG is used as the LC_CTYPE. If none of these three is set, the default locale "C" is used as the LC_CTYPE.

LC_COLLATE

LC_ALL controls the collation of characters, see above.

If this is unset and the LC_ALL is set, the LC_ALL is used as the LC_CTYPE. If both this and the LC_ALL are unset but the LANG is set, the LANG is used as the LC_COLLATE. If none of these three is set, the default locale "C" is used as the LC_COLLATE.

LANG

LC_ALL is the "catch-all" locale environment variable. If it is set, it is used as the last resort if neither of the LC_ALL and the category-specific LC_... are set.

There are further locale-controlling environment variables (LC_MESSAGES, LC_MONETARY, LC_NUMERIC, LC_TIME) but Perl does not currently obey them.

1 POD Error

The following errors were encountered while parsing the POD:

Around line 11:

Non-ASCII character seen before =encoding in 'naïve'. Assuming CP1252