========================================================================
CVE-2026-59146                                       CPAN Security Group
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         CVE ID:  CVE-2026-59146
   Distribution:  Data-SpatialHash-Shared
       Versions:  before 0.02

       MetaCPAN:  https://metacpan.org/dist/Data-SpatialHash-Shared
       VCS Repo: https://github.com/vividsnow/perl5-data-spatialhash-shared

Data::SpatialHash::Shared versions before 0.02 for Perl allow
out-of-bounds reads and writes via unvalidated bucket, link and
free-list indices in sph_walk_cell and sph_alloc_slot

Description
-----------
Data::SpatialHash::Shared versions before 0.02 for Perl allow
out-of-bounds reads and writes via unvalidated bucket, link and
free-list indices in sph_walk_cell and sph_alloc_slot.

The attach-time validator sph_validate_header checks the header scalars
and region layout against the file size, but does not validate the
array contents it then trusts. sph_walk_cell reads entries[buckets[b]]
and follows each entry's next link raw, and sph_alloc_slot writes
through a file-stored free_head index, none bounded against the entry
count (max_entries).

A local peer that can write the backing file can leave the header valid
while poisoning the bucket chain and free list, so a query reads
through an out-of-bounds bucket and next index and an insert writes
through an out-of-bounds free-list head, corrupting memory or crashing
the process.

Problem types
-------------
- CWE-787 Out-of-bounds Write
- CWE-125 Out-of-bounds Read

Workarounds
-----------
For deployments that cannot upgrade to 0.02, place the backing file in
a directory writable only by the owning user, so a local peer cannot
tamper with the bucket chain and free list.

Solutions
---------
Upgrade to Data::SpatialHash::Shared 0.02 or later, which bounds every
entry index against the entry count before dereferencing it.

References
----------
https://metacpan.org/release/EGOR/Data-SpatialHash-Shared-0.02/diff/EGOR/Data-SpatialHash-Shared-0.01#sphash.h
https://metacpan.org/release/EGOR/Data-SpatialHash-Shared-0.02/changes