---
id: "CVE-2026-110685"
kind: "vulnerability"
aliases: ["CVE-2026-110685"]
title: "Cpanel::JSON::XS: failed THAW call leaks memory, enabling denial of service"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["cpanel-json-xs", "package", "perl", "self-hosted"]
not_affected_if: ["default-config", "trusted-input-only"]
published_at: "2026-10-19T19:17:22+00:00"
first_seen_at: "2026-10-23T21:57:18+00:00"
updated_at: "2026-10-25T05:10:43+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-110685", "first_seen_at": "2026-10-23T21:57:18+00:00"}]
---

# Cpanel::JSON::XS: failed THAW call leaks memory, enabling denial of service

Cpanel::JSON::XS before 4.80 for Perl leaks the decoded arguments of a tagged value when the class THAW method dies during decode with allow_tags. An attacker who sends many rejected documents can make a long-running process that catches the error and keeps running 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'`
- Search dependencies for `allow_tags` usage in code that decodes untrusted input
- unknown

## Fix

- Upgrade Cpanel::JSON::XS to `4.80` or later
- unknown

## Timeline

- 2026-10-23T21:57:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-110685

## From the sources

Cpanel::JSON::XS versions before 4.80 for Perl leak the decoded arguments of a tagged value when its THAW method dies in decode_tag.

With allow_tags, a tagged value's class name and argument array are decoded and passed to the class's THAW method. Both are released only after THAW returns, so a THAW that dies leaves the whole decoded argument structure allocated.

Each rejected document leaks data of a size the sender chooses, so a process that catches the error and keeps running exhausts its memory.

---

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