# CVE-2026-95155: FasterXML jackson-mapper-asl stack overflow from deeply nested JSON

Source: https://junglewise.ai/threats/cve-2026-95155-fasterxml-jackson-1-x-confirmed-in-jackson-mapper-asl-versions-1  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-15. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-95155 · Severity: high · CVSS 7.5 · Published 2026-10-15

FasterXML Jackson is a JSON parsing library used in Java applications to convert JSON data into objects. An attacker can exploit a vulnerability by supplying deeply nested JSON input to cause a denial of service through uncontrolled stack overflow, crashing the application and disrupting service availability without triggering normal exception handling.

Vendors: [FasterXML](https://junglewise.ai/threats/vendors/fasterxml).

## Quick answers

**Is CVE-2026-95155 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-95155 being exploited in the wild.

**How severe is CVE-2026-95155?** High severity, with a CVSS score of 7.5, published 15 October 2026.

**Which products and versions are affected?** FasterXML Jackson-Mapper-Asl 1.8.3, 1.9.2, 1.9.11, 1.9.12, 1.9.13 and likely other 1.x versions.

**Is there a fix for CVE-2026-95155?** 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-2026-95155 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-95155?** Check whether you run FasterXML Jackson-Mapper-Asl 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

Jackson 1.x lacks configurable limits on JSON nesting depth; when ObjectMapper.readValue() processes deeply nested JSON arrays or objects, it recursively exhausts the JVM thread stack and throws java.lang.StackOverflowError instead of a catchable JsonProcessingException. This occurs with small-volume but deeply nested input (4000+ levels) and affects services parsing untrusted network input that only catch normal JSON exceptions.

## Affected products

- FasterXML jackson-mapper-asl 1.8.3, 1.9.2, 1.9.11, 1.9.12, 1.9.13 and likely other 1.x versions

## Timeline

- 2026-10-15: disclosed

## References

- [https://github.com/FasterXML/jackson-1](https://github.com/FasterXML/jackson-1)
- [https://github.com/FasterXML/jackson-1/issues/11](https://github.com/FasterXML/jackson-1/issues/11)