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🛡️ CVE-2026-0859 — typo3

🟠 CVSS 7.8 — High ✅ No Known Exploit CWE-502 NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool

Problem

Local platform users who can write to TYPO3’s mail‑file spool directory can craft a file that the system will automatically deserialize without any class restrictions. This flaw allows an attacker to inject and execute arbitrary PHP code in the public scope of the web server.

The vulnerability is triggered when TYPO3 is configured with $GLOBALS['TYPO3_CONF_VARS']['MAIL']['transport_spool_type'] = 'file'; and a scheduler task or cron job runs the command mailer:spool:send. The spool‑send operation performs the insecure deserialization that is at the core of this issue.

Solution

Update to TYPO3 versions 10.4.55 ELTS, 11.5.49 ELTS, 12.4.41 LTS, 13.4.23 LTS, 14.0.2 that fix the problem described.

Credits

Thanks to Vitaly Simonovich for reporting this issue, and to TYPO3 security team members Elias Häußler and Oliver Hader for fixing it.

References

  • [TYPO3-CORE-SA-2026-004](https://typo3.org/security/advisory/typo3-core-sa-2026-004)

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-0859 is classified as CWE-502: Deserialization of Untrusted Data. Serialised data from an untrusted source is reconstructed into objects, which can trigger code during the process.

Affected software

CVE-2026-0859 is recorded against 2 packages.

  • typo3 (from 14.0.0 up to 14.0.2)
  • typo3/cms-core (from 10.0.0 up to 10.4.55)

Timeline and source

Published on 13 January 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com
typo3.org

Other advisories for this package

typo3 has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-502: Deserialization of Untrusted Data) in other software:

Details

Severity HIGH
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE CWE-502
Public Exploit ✅ No
Source NVD
Published 2026-01-13
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
typo3 14.0.0 14.0.2
typo3/cms-core 10.0.0 10.4.55

Similar Threats

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