# CVE-2026-86511: java-json-tools jackson-coreutils resource exhaustion in BigDecimal serialization

Source: https://junglewise.ai/threats/cve-2026-86511-java-json-tools-jackson-coreutils-resource-exhaustion-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-08. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-86511 · Severity: medium · CVSS 5.3 · Published 2026-09-08

jackson-coreutils is a library used to process JSON data in Java applications. A vulnerability in its default configuration causes exponential memory consumption when serializing certain numeric values, allowing an attacker to crash the application with a small JSON payload. This denial-of-service condition requires no authentication and affects many downstream projects that depend on this library.

Technologies: [Java-Json-Tools Jackson-Coreutils](https://junglewise.ai/threats/technologies/jackson-coreutils). Vendors: [Java-Json-Tools](https://junglewise.ai/threats/vendors/java-json-tools).

## Quick answers

**Is CVE-2026-86511 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86511 being exploited in the wild.

**How severe is CVE-2026-86511?** Medium severity, with a CVSS score of 5.3, published 8 September 2026.

**Which products and versions are affected?** Java-Json-Tools Jackson-Coreutils 2.0.

**Is there a fix for CVE-2026-86511?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-86511 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-86511?** Check whether you run Java-Json-Tools Jackson-Coreutils 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.

## Technical details

The vulnerability is a resource exhaustion (CWE-400) affecting the BigDecimal.toPlainString() method in JacksonUtils.java. The default ObjectMapper configuration enables both USE_BIG_DECIMAL_FOR_FLOATS and WRITE_BIGDECIMAL_AS_PLAIN features. When untrusted JSON containing large-exponent numbers (e.g., 1e100000) is parsed and then serialized, toPlainString() allocates memory proportional to the exponent, causing amplification factors up to 250,000,000x. An attacker can send a small JSON payload (e.g., 20 bytes) to trigger OutOfMemoryError. The attack vector is network-accessible (any endpoint accepting JSON) and requires no authentication or user interaction. The vulnerability affects jackson-coreutils 2.0 and is inherited by downstream libraries including json-schema-validator (26K+ dependents).

## Affected products

- java-json-tools jackson-coreutils 2.0

## Timeline

- 2026-07-28: disclosed: Security vulnerability reported via GitHub issue #65
- 2026-09-08: advisory: CVE-2026-86511 published

## References

- [https://github.com/java-json-tools/jackson-coreutils/](https://github.com/java-json-tools/jackson-coreutils/)
- [https://github.com/java-json-tools/jackson-coreutils/issues/65](https://github.com/java-json-tools/jackson-coreutils/issues/65)

## Related threats

- [java-json-tools jackson-coreutils resource exhaustion in JSON Pointer parsing](https://junglewise.ai/threats/cve-2026-86513-java-json-tools-jackson-coreutils-resource-exhaustion-in-json)
- [java-json-tools jackson-coreutils server-side request forgery in JsonLoader](https://junglewise.ai/threats/cve-2026-86321-java-json-tools-jackson-coreutils-server-side-request-forgery-in)