# CVE-2026-68494: FasterXML jackson-core incomplete number length validation bypass

Source: https://junglewise.ai/threats/cve-2026-68494-fasterxml-jackson-core-incomplete-number-length-validation-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-04. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-68494 · Severity: info · CVSS 7.5 · Published 2026-08-04

Jackson-core, a widely-used JSON parsing library in Java applications, contains an incomplete fix for a number length validation bypass. Attackers can exploit the non-blocking parser by streaming specially-crafted JSON data in small chunks, causing it to accumulate excessive heap memory per connection. This allows denial-of-service attacks against reactive web frameworks such as Spring WebFlux and Quarkus that process untrusted JSON input.

Technologies: [FasterXML Jackson-Core](https://junglewise.ai/threats/technologies/jackson-core). Vendors: [FasterXML](https://junglewise.ai/threats/vendors/fasterxml).

## Quick answers

**Is CVE-2026-68494 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-68494 being exploited in the wild.

**How severe is CVE-2026-68494?** Informational severity, with a CVSS score of 7.5, published 4 August 2026.

**Which products and versions are affected?** FasterXML Jackson-Core 3.0.0 through 3.1.3.

**Is there a fix for CVE-2026-68494?** A patch was published on 2026-05-21: Fix commit landed; included in 2.22.0 and 3.2.0 onward Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-68494 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-68494?** Check whether you run FasterXML Jackson-Core 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 an incomplete fix to CVE-2026-18401 affecting the non-blocking UTF-8 JSON parser (NonBlockingUtf8JsonParserBase). The integer parsing paths in _startPositiveNumber(), _startNegativeNumber(), and _finishNumberIntegralPart() fail to invoke validateIntegerLength() when the parser exhausts input while in the MINOR_NUMBER_INTEGER_DIGITS state and returns NOT_AVAILABLE. This allows attackers to stream incomplete number values in many small chunks, causing _textBuffer.expandCurrentSegment() to grow unbounded by maxNumberLength (capped at 1000 digits) and instead constrained only by maxStringLength (20 MiB default)—a ~20,000x amplification. The attack requires only the ability to send data to a vulnerable parsing endpoint; no authentication or user interaction is needed. The synchronous parsers and non-blocking parser on complete buffered input are unaffected. Patches are available in jackson-core 2.18.6, 2.21.1, and later.

## Affected products

- FasterXML jackson-core 2.15.0 through 2.18.5, 2.19.0 through 2.21.0
- FasterXML jackson-core 3.0.0 through 3.1.3

## Timeline

- 2026-08-04: disclosed
- 2026-05-21: patched: Fix commit landed; included in 2.22.0 and 3.2.0 onward

## Related threats

- [Jackson Core denial of service via unbounded JSON property name allocation](https://junglewise.ai/threats/cve-2026-68498-streamreadconstraints-maxnamelength-default-50-000-characters-is)
- [FasterXML jackson-core denial of service in UTF8DataInputJsonParser](https://junglewise.ai/threats/cve-2026-89425-utf8datainputjsonparser-reportinvalidtoken-in-fasterxml-jackson)
- [FasterXML jackson-core regular expression denial of service in NumberInput](https://junglewise.ai/threats/cve-2026-89407-numberinput-lookslikevalidnumber-in-fasterxml-jackson-core-pre)
- [FasterXML jackson-core number length constraint bypass in async parser](https://junglewise.ai/threats/fasterxml-jackson-core-number-length-constraint-bypass-in-async-parser-78aa3f75)
- [FasterXML jackson-core memory exhaustion in async parser via chunked digits](https://junglewise.ai/threats/fasterxml-jackson-core-memory-exhaustion-in-async-parser-via-chunked-aac0fe2a)