CVE-2026-49740
CVE-2026-49740 is a Deserialization of Untrusted Data vulnerability in typo3/cms-core. O3 Security confirms whether CVE-2026-49740 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
TYPO3 CMS - Insecure Deserialization in Core API
Blast Radius
typo3/cms-core🐘typo3/cms-core🐘typo3/cms-core🐘typo3/cms-core🐘typo3/cms-coreReal-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 cache frontend (VariableFrontend) and persistent key-value store (Registry) deserialized PHP payloads without integrity validation or class restrictions. An attacker with write access to the underlying storage backend (cache store or sys_registry database table) could inject a crafted serialized payload to trigger PHP Object Injection, potentially exploiting a gadget chain to achieve Remote Code Execution or other high-impact effects. Exploiting this vulnerability requires direct local write access to the storage, such as the SQL database or file system. This issue affects TYPO3 CMS versions before 10.4.57, 11.0.0-11.5.50, 12.0.0-12.4.45, 13.0.0-13.4.30 and 14.0.0-14.3.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | typo3/cms-core | all versions | 10.4.57 |
| 🐘Packagist | typo3/cms-core | ≥ 11.0.0&&< 11.5.51 | 11.5.51 |
| 🐘Packagist | typo3/cms-core | ≥ 12.0.0&&< 12.4.46 | 12.4.46 |
| 🐘Packagist | typo3/cms-core | ≥ 13.0.0&&< 13.4.31 | 13.4.31 |
| 🐘Packagist | typo3/cms-core | ≥ 14.0.0&&< 14.3.3 | 14.3.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for typo3/cms-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update typo3/cms-core to 10.4.57 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49740 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 pinpoints whether CVE-2026-49740 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-49740. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-49740 in your dependencies?
O3 detects CVE-2026-49740 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.