CVE-2020-12723

Perl versions 5.x before 5.22.3-RC2 and 5.24 before 5.24.1-RC2 improperly remove '.' characters from the end of the includes directory array. This may allow local users to gain privileges via a Trojan horse module under the current working directory.

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

A vulnerability in Perl 5.30.0 through 5.38.0 allows a heap buffer overflow when compiling a crafted regular expression. An attacker can exploit this to cause a controlled buffer overflow.

A heap buffer overflow vulnerability was discovered in Perl. Affected versions include release branches 5.34, 5.36, 5.38, and 5.40, as well as development versions from 5.33.1 through 5.41.10. When non-ASCII bytes are present in the left-hand side of the `tr` operator, `S_do_trans_invmap` can overflow the buffer.

Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.10 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. Overflow of a 16-bit field truncates the match decision table, leading to false positive and false negative matches.

Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have a heap buffer overflow when compiling regular expressions with a repeated fixed string on 32-bit builds. The bug in Perl_study_chunk in regcomp_study.c checked buffer size in characters rather than bytes, leading to undersized allocation and out-of-bounds write.

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.

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

The VDir::MapPathA and VDir::MapPathW functions in Perl 5.22 allow remote attackers to cause a denial of service (out-of-bounds read) and possibly execute arbitrary code via a crafted (1) drive letter or (2) pInName argument.

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. This can lead to missed matches or matching on the wrong branch.