How severe is CVE-2026-0859?

No CVSS score has been assigned to CVE-2026-0859 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-0859?

CVE-2026-0859 affects the following packages: typo3/cms-core (Packagist), typo3/cms-core (Packagist), typo3/cms-core (Packagist), typo3/cms-core (Packagist), typo3/cms-core (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-0859?

Update typo3/cms-core to 14.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-0859 is resolved across your whole dependency graph.

How do I detect CVE-2026-0859 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for typo3/cms-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-0859 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-0859?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-0859 can be triaged on real exposure rather than presence alone.

Is CVE-2026-0859 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-0859 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-0859?

CVE-2026-0859 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 9th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-0859?

CVE-2026-0859 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-0859 published, and has it been updated?

CVE-2026-0859 was published on January 13, 2026 and was last updated on August 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-0859 — typo3/cms-core

Fix: TYPO3/typo3@3225d70

CVE-2026-0859 is a Deserialization of Untrusted Data vulnerability in typo3/cms-core. A fix is available for typo3/cms-core — see the affected versions and patch details below.

TYPO3 CMS Allows Insecure Deserialization via Mailer File Spool

Also known asGHSA-7vp9-x248-9vr9

Published

Jan 13, 2026

Updated

Aug 27, 2026

Affected

5 pkgs

Patched

5 / 5

Exploits

None indexed

Exploitation data as of Sep 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-0859.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs9th percentile — riskier than 9% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

5 pkgs affected

🐘typo3/cms-core🐘typo3/cms-core🐘typo3/cms-core🐘typo3/cms-core🐘typo3/cms-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

5 total 5 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`typo3/cms-core`	≥ 14.0.0&&< 14.0.2	14.0.2`composer require typo3/cms-core:^14.0.2`
🐘Packagist	`typo3/cms-core`	≥ 13.0.0&&< 13.4.23	13.4.23`composer require typo3/cms-core:^13.4.23`
🐘Packagist	`typo3/cms-core`	≥ 12.0.0&&< 12.4.41	12.4.41`composer require typo3/cms-core:^12.4.41`
🐘Packagist	`typo3/cms-core`	≥ 11.0.0&&< 11.5.49	11.5.49`composer require typo3/cms-core:^11.5.49`
🐘Packagist	`typo3/cms-core`	≥ 10.0.0&&< 10.4.55	10.4.55`composer require typo3/cms-core:^10.4.55`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for typo3/cms-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update typo3/cms-core to 14.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-0859 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-0859 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-0859. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2026-0859 in your dependencies?

O3 Security finds CVE-2026-0859 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works