CVE-2026-110879

9.8 CRITICALpublic exploit available

Published 2026-10-28 · Updated 2026-10-28

AI risk analysis

Summary: The flaw allows attackers to bypass generic-argument validation in jackson-databind by embedding unvalidated classes inside type ID generics (e.g., [Lpkg.Gadget;) even when those classes would be rejected as direct type IDs, due to incorrect validation logic that checks only the outer class and delegates to validators with mismatched expectations.
Exploitability: Exploitation requires sending a crafted JSON payload with a malicious class name in a polymorphic type ID field, but no authentication or user interaction is needed, and public exploits exist.
Blast radius: Successful exploitation could lead to remote code execution (RCE) via deserialization of arbitrary classes, compromising confidentiality, integrity, and availability of affected systems.
Detection: Defenders should monitor for deserialization attempts of unexpected or high-risk classes (e.g., java.lang.Runtime, javax.script.ScriptEngineManager) in JSON payloads logged by the application or API gateway; anomalies in type ID usage (e.g., nested generic class names with non-conforming outer/inner class relationships) may also be observable in structured logs.
Prioritized remediation: Upgrade to jackson-databind 2.19.0 or later, where the incomplete fix for CVE-2026-54512 has been corrected to properly validate generic arguments against their declared bindings.

rcedeserializationbypassjsonjackson

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

jackson-databind validates the outer class of a class-name type ID but accepts attacker-selected classes inside its generic arguments, even when those classes violate the declared type or would be rejected as direct type IDs. This bypasses the generic-argument validation added for CVE-2026-54512 (GHSA-j3rv-43j4-c7qm), of which this is an incomplete fix. DatabindContext._resolveAndValidateGeneric() checks the outer class against the declared base type and then passes each argument from the type ID to _validateTypeParameter(), which validates the argument against the outer base type rather than enforcing its corresponding declared generic binding. It also invokes validators with arguments that have not passed the subtype check those validators expect. Under the default DefaultBaseTypeLimitingValidator this accepts an unrelated class inside a generic subtype even when the same class is rejected as a direct type ID. Where an allowIfBaseType(...) rule approves the outer type, Jackson substitutes LaissezFaireSubTypeValidator, so the configured validator no longer restricts the embedded arguments. The element type of a plain array type ID such as [Lpkg.Gadget; is likewise left unvalidated once the array's base type is approved. Affected paths include annotation-based class-name polymorphism with a default Jackson 3.x JsonMapper, configured default typing in both Jackson 2.x and 3.x, and integrations that expose that default typing. The default-validator case requires no application-authored validator: with @JsonTypeInfo(use = Id.CLASS), a direct gadget type ID is rejected as "Not a subtype", while a type ID naming a generic wrapper around the same gadget is accepted and deserialized, including attacker-supplied bean properties. Where class-name default typing permits Map, a property declared as Map<String,String> accepts HashMap<FileSystemXmlApplicationContext,String>; map-key discovery then passes the attacker-controlled JSON property name to the selected class's one-string constructor. With Spring on the classpath and attacker-controlled XML the application can load, that constructor loads the XML and invokes ProcessBuilder.start() under the application account, giving arbitrary command execution. This issue affects com.fasterxml.jackson.core:jackson-databind from 2.10.0 and tools.jackson.core:jackson-databind from 3.0.0. Releases before 2.10.0 are not affected, because PolymorphicTypeValidator was introduced in jackson-databind 2.10.0.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

CWE-502

Public exploit & PoC references

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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