CVE-2026-110674: 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

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-19 · updated 2026-10-29
Weakness: CWE-176

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.

Affected products

Cpanel-JSON-XS: from 4.33 before 4.80 — fixed in 4.80

How to fix

Upgrade to a fixed version: Cpanel-JSON-XS 4.80. Check the vendor advisory for mitigations.

References

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