# CVE-2026-110672: Cpanel::JSON::XS memory leak in decode_hv with rejected keys

Source: https://junglewise.ai/threats/cve-2026-110672-cpanel-json-xs-versions-before-4-80-for-perl-leak-the-decoded  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-19. Updated: 2026-10-19  
License: CC BY 4.0 with a link back

CVE-2026-110672 · Severity: info · Published 2026-10-19

Cpanel::JSON::XS is a JSON parser for Perl that converts JSON text into Perl data structures. A memory leak occurs when the parser rejects JSON objects due to duplicate keys or missing colons, causing the decoded key to remain in memory. An attacker sending repeated malformed JSON to a long-running process can exhaust available memory and cause the application to crash or become unresponsive.

Technologies: [cPanel JSON::XS](https://junglewise.ai/threats/technologies/json-xs). Vendors: [cPanel](https://junglewise.ai/threats/vendors/cpanel).

## Quick answers

**Is CVE-2026-110672 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-110672 being exploited in the wild.

**How severe is CVE-2026-110672?** Informational severity, published 19 October 2026.

**Which products and versions are affected?** cPanel JSON::XS before 4.80.

**Is there a fix for CVE-2026-110672?** Yes: fixed in Cpanel::JSON::XS 4.80. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-110672 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-110672?** Check whether you run cPanel JSON::XS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Cpanel::JSON::XS 4.80

## Technical details

The vulnerability exists in the decode_hv function where decoded object keys (24+ bytes, containing non-ASCII characters, or escape sequences) are allocated as scalars but not freed when the object is rejected for a missing colon after the key or for duplicate keys (when allow_dupkeys, dupkeys_as_arrayref, or relaxed modes are disabled). An attacker with network access can send crafted JSON payloads to exhaust process memory through repeated rejections. The fix adds proper reference counting cleanup (SvREFCNT_dec) in error paths.

## Affected products

- Cpanel JSON::XS before 4.80

## Timeline

- 2026-10-19: disclosed
- 2026-10-14: patched: Fix committed as CVE-2026-110672

## References

- [https://cpan.org/modules](https://cpan.org/modules)
- [https://github.com/rurban/Cpanel-JSON-XS/commit/532b53cf8d2ca5ab6bc24048325566d1f7132425.patch](https://github.com/rurban/Cpanel-JSON-XS/commit/532b53cf8d2ca5ab6bc24048325566d1f7132425.patch)

## Related threats

- [Cpanel::JSON::XS canonical encoding misorders byte-string keys](https://junglewise.ai/threats/cve-2026-110687-cpanel-json-xs-versions-from-4-43-before-4-80-for-perl-misorder)
- [Cpanel::JSON::XS incremental parser number ambiguity in incr_parse](https://junglewise.ai/threats/cve-2026-110682-cpanel-json-xs-versions-from-4-42-before-4-80-for-perl-let-input)
- [Cpanel::JSON::XS memory leak in dupkeys_as_arrayref](https://junglewise.ai/threats/cve-2026-110677-cpanel-json-xs-versions-from-4-28-before-4-80-for-perl-leak-the)
- [Cpanel::JSON::XS type confusion in duplicate key handling](https://junglewise.ai/threats/cve-2026-110674-cpanel-json-xs-versions-from-4-33-before-4-80-for-perl-miss)
- [Cpanel::JSON::XS stack exhaustion in decode_tag with allow_tags](https://junglewise.ai/threats/cve-2026-110673-cpanel-json-xs-versions-before-4-80-for-perl-allow-stack)