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perl-5.42.2
⭐ Starred 2013 / B::Terse
Security Advisories (3)
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-2026-13221 (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-2026-8376 (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

B::Terse - Walk Perl syntax tree, printing terse info about ops

SYNOPSIS

perl -MO=Terse[,OPTIONS] foo.pl

DESCRIPTION

This module prints the contents of the parse tree, but without as much information as CPAN module B::Debug. For comparison, print "Hello, world." produced 96 lines of output from B::Debug, but only 6 from B::Terse.

This module is useful for people who are writing their own back end, or who are learning about the Perl internals. It's not useful to the average programmer.

This version of B::Terse is really just a wrapper that calls B::Concise with the -terse option. It is provided for compatibility with old scripts (and habits) but using B::Concise directly is now recommended instead.

For compatibility with the old B::Terse, this module also adds a method named terse to B::OP and B::SV objects. The B::SV method is largely compatible with the old one, though authors of new software might be advised to choose a more user-friendly output format. The B::OP terse method, however, doesn't work well. Since B::Terse was first written, much more information in OPs has migrated to the scratchpad datastructure, but the terse interface doesn't have any way of getting to the correct pad. As a kludge, the new version will always use the pad for the main program, but for OPs in subroutines this will give the wrong answer or crash.

AUTHOR

The original version of B::Terse was written by Malcolm Beattie, <mbeattie@sable.ox.ac.uk>. This wrapper was written by Stephen McCamant, <smcc@MIT.EDU>.