Vulnerability · Published Jun 3, 2026 · Assigned by CPANSec
CVE-2026-9516Cpanel::JSON::XS versions before 4.41 for Perl allow denial of service via UTF-8 BOM prefixed input when a decode filter callback throws
High 7.5
In plain English
A high-severity security flaw in Cpanel::JSON::XS from RURBAN. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | libcpanel-json-xs-perl | no fix listed | DEBIAN-CVE-2026-9516 |
| Debian:13 | libcpanel-json-xs-perl | no fix listed | DEBIAN-CVE-2026-9516 |
| Debian:14 | libcpanel-json-xs-perl | 4.41-1 | DEBIAN-CVE-2026-9516 |
| Ubuntu:22.04:LTS | libcpanel-json-xs-perl | no fix listed | UBUNTU-CVE-2026-9516 |
| Ubuntu:24.04:LTS | libcpanel-json-xs-perl | no fix listed | UBUNTU-CVE-2026-9516 |
| Ubuntu:25.10 | libcpanel-json-xs-perl | no fix listed | UBUNTU-CVE-2026-9516 |
| Ubuntu:26.04:LTS | libcpanel-json-xs-perl | no fix listed | UBUNTU-CVE-2026-9516 |
| Ubuntu:26.10 | libcpanel-json-xs-perl | no fix listed | UBUNTU-CVE-2026-9516 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RURBAN | Cpanel::JSON::XS | 0 – before 4.41 |
Weakness: CWE-763, CWE-755 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H