COMPOSER · MAY 2026 · EARLY WARNING

TYPO3 'Content Element Selector' Extension Under Investigation for RCE

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.

GHSA-8X3J-439W-537CSeverity: HIGH

The TYPO3 'Content Element Selector' extension is under investigation for a potential Remote Code Execution vulnerability. Users of this extension should assess their exposure and consider upgrading.

What happened

An early warning has been issued regarding a potential Remote Code Execution (RCE) vulnerability in the TYPO3 'Content Element Selector' extension. This vulnerability, tracked as GHSA-8X3J-439W-537C, appears to allow unauthenticated attackers to execute arbitrary code via PHP Object Injection by supplying a crafted serialized payload. The vulnerability has been patched in versions 3.0.3, 4.0.2, 5.0.1, and 6.0.1 of the 'composer/mmc/ceselector' package. Users are advised to upgrade to one of these versions to mitigate the risk. For more details, consult the primary sources.

How 0Day mitigates this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If composer/mmc/ceselector is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

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