---
id: "CVE-2026-110672"
kind: "vulnerability"
aliases: ["CVE-2026-110672"]
title: "Cpanel::JSON::XS: rejected JSON objects leak memory, repeated requests exhaust process memory"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["cpanel-json-xs", "package", "perl", "self-hosted", "web-services"]
not_affected_if: ["not-installed", "short-lived-processes", "trusted-input-only"]
published_at: "2026-10-19T19:17:20+00:00"
first_seen_at: "2026-10-23T21:57:18+00:00"
updated_at: "2026-10-25T05:10:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-110672", "first_seen_at": "2026-10-23T21:57:18+00:00"}]
---

# Cpanel::JSON::XS: rejected JSON objects leak memory, repeated requests exhaust process memory

Cpanel::JSON::XS before 4.80 for Perl leaks the decoded key of a JSON object rejected for a duplicate key or a missing colon. A long-running process that keeps handling bad documents accumulates one leaked key per rejected document, so repeated requests can exhaust its memory.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version with `perl -MCpanel::JSON::XS -e 'print $Cpanel::JSON::XS::VERSION'`, or `cpanm --info Cpanel::JSON::XS`.
- Search dependency manifests and lockfiles for `Cpanel::JSON::XS` below `4.80`.
- Check whether decode calls leave out allow_dupkeys, dupkeys_as_arrayref and relaxed, and whether the process accepts untrusted JSON for a long time.

## Fix

- Upgrade Cpanel::JSON::XS to `4.80` or later.
- Restart long-running worker processes after upgrading so leaked memory is released.

## Timeline

- 2026-10-23T21:57:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-110672

## From the sources

Cpanel::JSON::XS versions before 4.80 for Perl leak the decoded key of an object rejected for a duplicate key or a missing colon in decode_hv.

A quoted key of 24 or more bytes, or one containing a non-ASCII byte or an escape sequence, is decoded into a new scalar. Nothing frees that scalar when the object is rejected for a missing ':' after the key or, from 4.09, for a duplicate key. Duplicate keys are an error unless allow_dupkeys, dupkeys_as_arrayref or relaxed is set.

A process that keeps running after a failed decode retains one key per rejected document, with its size chosen by the sender. Repeated requests exhaust process memory.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_