---
id: "CVE-2026-110678"
kind: "vulnerability"
aliases: ["CVE-2026-110678"]
title: "Cpanel::JSON::XS: incremental parser buffers input past max_size, exhausting memory"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["cpanel-json-xs", "network-services", "package", "perl"]
not_affected_if: ["no-incr-parse", "trusted-input-only"]
published_at: "2026-10-19T19:17:21+00:00"
first_seen_at: "2026-10-23T21:57:18+00:00"
updated_at: "2026-10-25T05:10:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-110678", "first_seen_at": "2026-10-23T21:57:18+00:00"}]
---

# Cpanel::JSON::XS: incremental parser buffers input past max_size, exhausting memory

Cpanel::JSON::XS before 4.80 appends incremental input chunks without enforcing max_size when a chunk starts with a NUL byte or the call is in void context. A peer streaming data to an incr_parse consumer can grow the buffer until process memory is exhausted.

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

## How to check

- Run `perl -MCpanel::JSON::XS -e 'print $Cpanel::JSON::XS::VERSION'` and look for a version below `4.80`
- Search application code for `incr_parse` calls that read from network sockets or untrusted streams

## Fix

- Upgrade Cpanel::JSON::XS to `4.80` or later
- Until upgraded, avoid feeding untrusted peer data to `incr_parse` or enforce a size limit on the input stream before parsing

## Timeline

- 2026-10-23T21:57:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-110678

## From the sources

Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by buffering incremental input past max_size in incr_parse.

The parser appends each chunk to its buffer. In scalar or list context, it compares max_size with how far it has progressed, not with the buffer length. A chunk that starts with a NUL byte stops the parser before it progresses, and a call in void context skips the check, so the buffer grows without limit.

A peer streaming data to an incr_parse consumer can exhaust process memory regardless of max_size.

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