Jackson-Databind PTV Array Type Allowlist Bypass 2.10.0-2.18.8, 2.21.4, 3.1.4
CVE-2026-54513 Published on June 23, 2026
jackson-databind: Array subtype allowlist bypass in BasicPolymorphicTypeValidator (allowIfSubTypeIsArray)
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, BasicPolymorphicTypeValidator.Builder.allowIfSubTypeIsArray() allowlists any array type based only on clazz.isArray(), without validating the array's component (element) type against the configured allowlist. A PTV built with allowIfSubTypeIsArray() plus an explicit concrete-type allowlist therefore still permits EvilType[] even though EvilType is not allowlisted. When Jackson deserializes the elements and no per-element type IDs are present, it instantiates the component type directly with no further PTV check, bypassing the allowlist. This vulnerability is fixed in 2.18.8, 2.21.4, and 3.1.4.
Vulnerability Analysis
CVE-2026-54513 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Denylist / Deny List Vulnerability?
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Developers often try to protect their products against malicious input by performing tests against inputs that are known to be bad, such as special characters that can invoke new commands. However, such lists often only account for the most well-known bad inputs. Attackers may be able to find other malicious inputs that were not expected by the developer, allowing them to bypass the intended protection mechanism.
CVE-2026-54513 has been classified to as a Denylist / Deny List vulnerability or weakness.
Products Associated with CVE-2026-54513
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Affected Versions
FasterXML jackson-databind:- Version >= 2.10.0, < 2.18.8 is affected.
- Version >= 2.19.0, < 2.21.4 is affected.
- Version >= 3.0.0, < 3.1.4 is affected.