CVE-2026-54512
HighCVSS 8.1Exploitation Probability (EPSS)
Low risk45th percentile — higher than 45% of all known CVEs
Summary
Vulnerability in jackson-databind allows bypassing the PolymorphicTypeValidator (PTV) during polymorphic deserialization. When a type contains generic parameters (e.g., ArrayList<Gadget>), validation only checks the container name, not nested types, enabling loading a denied class as a generic parameter.
Risk Assessment
An attacker can achieve remote code execution (RCE) by crafting JSON that uses an allowed container (e.g., ArrayList) to load and instantiate a forbidden class (e.g., gadget).
Recommendation
Immediately update jackson-databind to version 2.18.8, 2.21.4, or 3.1.4. If updating is not possible, disable polymorphic deserialization or use additional safeguards (e.g., application-level whitelist).
Original NVD description (English source)
jackson-databind contains the general-purpose data-binding functionality and tree-model for Jackson Data Processor. From 2.10.0 until 2.18.8, 2.21.4, and 3.1.4, jackson-databind's PolymorphicTypeValidator (PTV) is the primary safety mechanism guarding polymorphic deserialization. When polymorphic typing is enabled and a type identifier contains generic parameters (i.e. the type ID string contains <), DatabindContext._resolveAndValidateGeneric() validates only the raw container class name (the substring before <) against the configured PTV. If the container type is approved, the method parses the full canonical type string via TypeFactory.constructFromCanonical() and returns the fully parameterized type without ever validating the nested type arguments against the PTV. The nested type arguments are then resolved, instantiated, and populated as beans during deserialization. An attacker who controls the type ID can therefore place a denied class as a generic type parameter of an allowed container — for example java.util.ArrayList<com.evil.Gadget> when only java.util.ArrayList is allow-listed. The container passes the PTV check; com.evil.Gadget is loaded via Class.forName(name, true, loader), instantiated, and its properties are set from attacker-controlled JSON. This completely bypasses an explicitly configured PTV allow-list. This vulnerability is fixed in 2.18.8, 2.21.4, and 3.1.4.