CVE-2026-0859
TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool
Description
### 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 to fix CVE-2026-0859
To remediate CVE-2026-0859, upgrade the affected package to a fixed version below.
- —upgrade to 14.0.2 or later
Is CVE-2026-0859 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 14.0.0, < 14.0.2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |