========================================================================
CVE-2026-9516 CPAN Security Group
========================================================================
CVE ID: CVE-2026-9516
Distribution: Cpanel-JSON-XS
Versions: before 4.41
MetaCPAN: https://metacpan.org/dist/Cpanel-JSON-XS
VCS Repo: https://github.com/rurban/Cpanel-JSON-XS
Cpanel::JSON::XS versions before 4.41 for Perl allow denial of service
via UTF-8 BOM prefixed input when a decode filter callback throws
Description
-----------
Cpanel::JSON::XS versions before 4.41 for Perl allow denial of service
via UTF-8 BOM prefixed input when a decode filter callback throws.
To skip a leading 3-byte UTF-8 BOM, decode_json() advances the input
scalar's string pointer past the mark with SvPV_set() and restores it
only on the normal return path. When decoding aborts through a Perl
exception, for example a filter_json_object callback that croaks, the
restore is skipped and the scalar is left with its string pointer
offset into its own buffer and a shortened length.
When that scalar is later freed, the allocator receives an invalid
pointer and the interpreter aborts. A single BOM prefixed document
decoded with a throwing filter callback crashes any caller.
Problem types
-------------
- CWE-763 Release of Invalid Pointer or Reference
- CWE-755 Improper Handling of Exceptional Conditions
Solutions
---------
Upgrade to Cpanel::JSON::XS 4.41 or later.
References
----------
https://github.com/rurban/Cpanel-JSON-XS/commit/dfe1b41a36caba51dc12a2917fe50285d1ffaa7b.patch
https://metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.41/changes
Timeline
--------
- 2026-05-18: Issue reported.
- 2026-05-27: Version 4.41 released with fix.
- 2026-05-28: Fix verified.
--
Paul Johnson - [email protected]
