Description
Cpanel::JSON::XS versions before 4.41 for Perl allow type confusion via duplicate object keys when dupkeys_as_arrayref is enabled. decode_hv() collapses duplicate object keys into an array reference under dupkeys_as_arrayref. The branch reached for a duplicate key tests `SvTYPE (old_value) != SVt_RV && SvTYPE (SvRV (old_value)) != SVt_PVAV`, which evaluates SvRV(old_value) before establishing that old_value is a reference. When the existing value is a plain scalar rather than an array reference, a non-reference scalar is dereferenced as a reference. A caller decoding untrusted JSON with dupkeys_as_arrayref enabled is crashed, and the incompatible access follows a pointer taken from attacker controlled scalar contents.
Problem types
CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')
Product status
Any version before 4.41
Timeline
| 2026-02-24: | Issue reported. |
| 2026-05-27: | Version 4.41 released with fix. |
| 2026-05-28: | Fix verified. |
References
www.openwall.com/lists/oss-security/2026/06/03/4
github.com/...11a7c550a0d8fac2f84414f24d5df9b2bfe346e2.patch
metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.41/changes