Summary
Problem
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.
Credits
TYPO3 CMS thanks “z3rco”, Chowdhury Faizal Ahammed, Rick Larabee, Vitaly Simonovich, Nozomu Sasaki, Mert Akdag, “tikket”, Shafi Almutairi for reporting this issue, and to TYPO3 core & security team member Oliver Hader for fixing it.
Resources
Impact
Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Update to TYPO3 versions 10.4.57 ELTS, 11.5.51 ELTS, 12.4.46 ELTS, 13.4.31 LTS, 14.3.3 LTS that fix the problem described.
Frequently Asked Questions
- What is CVE-2026-49740? CVE-2026-49740 is a medium-severity insecure deserialization vulnerability in typo3/cms-core (composer), affecting versions < 10.4.57. It is fixed in 10.4.57, 11.5.51, 12.4.46, 13.4.31, 14.3.3. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
- Which versions of typo3/cms-core are affected by CVE-2026-49740? typo3/cms-core (composer) versions < 10.4.57 is affected.
- Is there a fix for CVE-2026-49740? Yes. CVE-2026-49740 is fixed in 10.4.57, 11.5.51, 12.4.46, 13.4.31, 14.3.3. Upgrade to this version or later.
- Is CVE-2026-49740 exploitable, and should I be worried? Whether CVE-2026-49740 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-49740 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-49740?
- Upgrade
typo3/cms-coreto 10.4.57 or later - Upgrade
typo3/cms-coreto 11.5.51 or later - Upgrade
typo3/cms-coreto 12.4.46 or later - Upgrade
typo3/cms-coreto 13.4.31 or later - Upgrade
typo3/cms-coreto 14.3.3 or later
- Upgrade