Out-of-bounds read crash in Perl Algorithm::AhoCorasick::XS
Algorithm::AhoCorasick::XS through 0.04 reads the haystack scalar's length with SvCUR before the value is stringified when matches, first_match, or match_details build a C++ string. If the haystack is a number, a float, a reference, a blessed object, a decoded JSON number, or a numeric database column, that length can be wrong and the module performs an out-of-bounds read that aborts the Perl process. Argument evaluation order is unspecified, so on some compilers the abort cannot be caught inside Perl. Anyone embedding this XS module and passing non-string haystacks is affected. It is not listed in CISA KEV, has no CVSS score yet, and no public exploit is known.
What to do: Treat every haystack passed to matches, first_match, or match_details as a string: stringify numbers, decoded JSON values, numeric database columns, and objects before the call. Upgrade Algorithm::AhoCorasick::XS once a release newer than 0.04 is available, and until then avoid feeding non-string scalars into those methods so a bad length cannot abort the process.
| Product | Affected |
|---|---|
| CPAN Algorithm::AhoCorasick::XS | through 0.04 |
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Algorithm::AhoCorasick::XS versions through 0.04 for Perl read the haystack string length before the scalar is stringified. The matches, first_match and match_details methods use the T_STD_STRING typemap to translate Perl scalars (SVs) into strings via the std::string constructor, using the SvPV macro to stringify the haystack input, and the SvCUR macro to determine the length of the SV. When the input SVs are references, integers (IVs) or floats (NVs), the SvCUR macro will return an invalid length if it is run before the input is stringified, leading to an out-of-bounds read which can abort the process. Note that the evaluation order of arguments to std::string is unspecified. Depending on the compiler, SvCUR may be run first and lead to an abort that cannot be caught within Perl. This can be triggered when the haystack is a numeric value, for example, my $ac = Algorithm::AhoCorasick::XS->new( [ "11", "22" ] ); $ac->matches( 211 ); This can occur when the haystack is the result of reading data from decoded JSON or a numeric database column. It can also be triggered when using a blessed object as a haystack.
CVE-2026-80490 in Perl's Algorithm::AhoCorasick::XS through 0.04 reads haystack length before scalar stringification, causing incorrect search behavior.
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