Cpanel::JSON::XS versions from 4.33 before 4.80 for Perl miss duplicate non-ASCII bare keys…

Why it is Yellow

• CVSS 6.5 medium

References

• https://github.com/rurban/Cpanel-JSON-XS/commit/c52037857d6a99d96ebd1ce3e2fa769505f028cf.patch
• https://metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.80/changes
• https://www.cve.org/CVERecord?id=CVE-2026-9334

Original description

Cpanel::JSON::XS versions from 4.33 before 4.80 for Perl miss duplicate non-ASCII bare keys, allowing type confusion under dupkeys_as_arrayref in decode_hv. With allow_barekey, which relaxed enables, a bare key containing a non-ASCII byte is stored as UTF-8 but looked up as raw bytes, so a repeated key escapes the duplicate-key check and replaces the earlier value. From 4.41, under dupkeys_as_arrayref, a bare repeat replaces the array that collects a key's values with a plain value, and the next quoted repeat pushes onto that value as if it were an array. A JSON integer there is dereferenced as a pointer. Untrusted JSON decoded with relaxed and dupkeys_as_arrayref can crash the process or dereference an address chosen by a JSON number.