# CVE-2026-54513: FasterXML jackson-databind validation bypass in BasicPolymorphicTypeValidator

Source: https://junglewise.ai/threats/cve-2026-54513-fasterxml-jackson-databind-validation-bypass-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-23. Updated: 2026-06-23  
License: CC BY 4.0 with a link back

CVE-2026-54513 · Severity: high · CVSS 8.1 · Published 2026-06-23

FasterXML jackson-databind is a popular Java library used for converting data between Java objects and formats like JSON. A security flaw in its validation mechanism allows an attacker to bypass security allowlists by using array types. This could lead to the execution of unauthorized code or other malicious actions when the application processes specially crafted data.

Technologies: [FasterXML Jackson Databind](https://junglewise.ai/threats/technologies/jackson-databind), [com.fasterxml.jackson.core:jackson-databind (Maven)](https://junglewise.ai/threats/technologies/com-fasterxml-jackson-core-jackson-databind), [tools.jackson.core:jackson-databind (Maven)](https://junglewise.ai/threats/technologies/tools-jackson-core-jackson-databind). Vendors: [FasterXML](https://junglewise.ai/threats/vendors/fasterxml), [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2026-54513 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54513 being exploited in the wild.

**How severe is CVE-2026-54513?** High severity, with a CVSS score of 8.1, published 23 June 2026.

**Which products and versions are affected?** FasterXML Jackson Databind >= 2.10.0, < 2.18.8; >= 2.19.0, < 2.21.4; >= 3.0.0, < 3.1.4; com.fasterxml.jackson.core:jackson-databind (Maven) ECOSYSTEM:introduced=2.10.0,fixed=2.18.8; tools.jackson.core:jackson-databind (Maven) ECOSYSTEM:introduced=3.0.0,fixed=3.1.4.

**Is there a fix for CVE-2026-54513?** Yes. com.fasterxml.jackson.core:jackson-databind (Maven): upgrade to 2.18.8 or later; tools.jackson.core:jackson-databind (Maven): upgrade to 3.1.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54513 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-54513?** Check whether you run FasterXML Jackson Databind, com.fasterxml.jackson.core:jackson-databind (Maven) or tools.jackson.core:jackson-databind (Maven) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- com.fasterxml.jackson.core:jackson-databind (Maven): upgrade to 2.18.8 or later

  ```sh
  # set com.fasterxml.jackson.core:jackson-databind to 2.18.8 in your pom.xml or build.gradle
  ```

- tools.jackson.core:jackson-databind (Maven): upgrade to 3.1.4 or later

  ```sh
  # set tools.jackson.core:jackson-databind to 3.1.4 in your pom.xml or build.gradle
  ```


## Technical details

A vulnerability exists in jackson-databind's BasicPolymorphicTypeValidator (PTV) where the allowIfSubTypeIsArray() method fails to validate the component type of an array against the configured allowlist. While the validator correctly checks if a class is an array, it does not perform a secondary check on the element type during deserialization if per-element type IDs are missing. This allows an attacker to bypass PTV restrictions by wrapping a forbidden 'EvilType' in an array (e.g., EvilType[]), leading to the instantiation of unauthorized classes. The issue is fixed in versions 2.18.8, 2.21.4, and 3.1.4.

## Affected products

- FasterXML jackson-databind >= 2.10.0, < 2.18.8; >= 2.19.0, < 2.21.4; >= 3.0.0, < 3.1.4

## Identifiers

- CVE-2026-54513
- GHSA-rmj7-2vxq-3g9f

## Timeline

- 2026-05-08: patched: Fixes committed to 2.18 and 3.x branches
- 2026-06-23: disclosed: CVE published to NVD

## References

- [https://github.com/FasterXML/jackson-databind/commit/01d1692c8d0ed03e51a0e3c4f8a9e6908e4931e5](https://github.com/FasterXML/jackson-databind/commit/01d1692c8d0ed03e51a0e3c4f8a9e6908e4931e5)
- [https://github.com/FasterXML/jackson-databind/commit/24529da29fdf46ff94ca38de9ebf31cd188f5e8e](https://github.com/FasterXML/jackson-databind/commit/24529da29fdf46ff94ca38de9ebf31cd188f5e8e)
- [https://github.com/FasterXML/jackson-databind/issues/5981](https://github.com/FasterXML/jackson-databind/issues/5981)
- [https://github.com/FasterXML/jackson-databind/issues/5983](https://github.com/FasterXML/jackson-databind/issues/5983)
- [https://github.com/FasterXML/jackson-databind/pull/5984](https://github.com/FasterXML/jackson-databind/pull/5984)
- [https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-rmj7-2vxq-3g9f](https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-rmj7-2vxq-3g9f)

## Related threats

- [jackson-databind type validation bypass in generic arguments](https://junglewise.ai/threats/cve-2026-110879-jackson-databind-validates-the-outer-class-of-a-class-name-type)
- [Jackson Protobuf Parser integer overflow in string key parsing](https://junglewise.ai/threats/cve-2026-110747-protobufparser-readstringkey-reads-the-length-prefix-of-a)
- [jackson-databind quadratic complexity in forward-reference resolution](https://junglewise.ai/threats/cve-2026-91777-jackson-databind-quadratic-forward-reference-completion)
- [FasterXML Jackson Databind unbounded cache growth on unknown type IDs](https://junglewise.ai/threats/cve-2026-91776-jackson-databind-retains-every-unknown-raw-type-id)
- [FasterXML jackson-databind quadratic parse in XML datatype deserialization](https://junglewise.ai/threats/cve-2026-68497-fasterxml-jackson-databind-quadratic-parse-in-xml-datatype)