Cpanel::JSON::XS: Improper Handling of Exceptional Conditions
CVE-2026-9516 is a high-severity improper handling of exceptional conditions vulnerability in Cpanel::JSON::XS from Rurban, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 4.41 as the first without the flaw, so updating Cpanel::JSON::XS to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.36% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Cpanel::JSON::XS to 4.41 or a later version.
- Update Cpanel to 4.41 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| RURBAN | Cpanel::JSON::XS | before 4.41 | 4.41 |
| Rurban | Cpanel | before 4.41 | 4.41 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CISA (ADP).
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Handling of Exceptional Conditions
The product does not handle or incorrectly handles an exceptional condition.
More Improper Handling of Exceptional Conditions vulnerabilities (CWE-755)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/rurban/Cpanel-JSON-XS/commit/dfe1b41a36caba51dc12a2917fe50285d1ffaa7b.patch
- metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.41/changesRelease Notes
- openwall.com/lists/oss-security/2026/06/03/5Mailing List, Third Party Advisory
Other vulnerabilities in Cpanel::JSON::XS
- 7.3 High severity
Recent Improper Handling of Exceptional Conditions vulnerabilities
- 7.5 High severity
- 7.3 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
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