CVE-2026-89425: FasterXML jackson-core denial of service in UTF8DataInputJsonParser

CVE-2026-89425 · Severity: high · CVSS 7.5 · Published 2026-09-23

FasterXML jackson-core is a JSON parsing library used in many Java applications. A flaw in how it processes malformed JSON tokens via the DataInput interface can cause the parser to accumulate extremely large error messages in memory, potentially consuming gigabytes of RAM and crashing the entire JVM. An attacker sending a single specially crafted malformed JSON token could trigger an out-of-memory condition affecting all applications using the library.

Technologies: FasterXML Jackson-Core, com.fasterxml.jackson.core:jackson-core (Maven), tools.jackson.core:jackson-core (Maven). Vendors: FasterXML, Maven.

Quick answers

Is CVE-2026-89425 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-89425 being exploited in the wild.
How severe is CVE-2026-89425?
High severity, with a CVSS score of 7.5, published 23 September 2026.
Which products and versions are affected?
FasterXML Jackson-Core 2.8.0 through 2.17.x; com.fasterxml.jackson.core:jackson-core (Maven) ECOSYSTEM:introduced=2.19.0,fixed=2.21.7; tools.jackson.core:jackson-core (Maven) ECOSYSTEM:introduced=3.0.0,fixed=3.1.7.
Is there a fix for CVE-2026-89425?
Yes. com.fasterxml.jackson.core:jackson-core (Maven): upgrade to 2.21.7 or later; tools.jackson.core:jackson-core (Maven): upgrade to 3.1.7 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-89425 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-89425?
Check whether you run FasterXML Jackson-Core, com.fasterxml.jackson.core:jackson-core (Maven) or tools.jackson.core:jackson-core (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-core (Maven): upgrade to 2.21.7 or later
    # set com.fasterxml.jackson.core:jackson-core to 2.21.7 in your pom.xml or build.gradle
  • tools.jackson.core:jackson-core (Maven): upgrade to 3.1.7 or later
    # set tools.jackson.core:jackson-core to 3.1.7 in your pom.xml or build.gradle

Technical details

The UTF8DataInputJsonParser class lacks bounds checking when building error message text for invalid tokens, unlike its sibling parser implementations. It fails to call ErrorReportConfiguration.getMaxErrorTokenLength() and does not respect StreamReadConstraints, allowing unbounded accumulation of token characters in a StringBuilder. When a DataInput source receives a 20-million-character malformed token, the resulting error message and internal array doubling can trigger OutOfMemoryError, whereas the same payload is limited to 256 characters on InputStream paths.

Affected products

  • FasterXML jackson-core 2.8.0 through 2.17.x

Identifiers

  • CVE-2026-89425
  • GHSA-7hhh-6rmp-j9qf

Timeline

  • 2026-09-23: disclosed: CVE-2026-89425 published
  • 2026-09-11: patched: Fix merged in PR #1698 to FasterXML/jackson-core:2.18

References

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