Jawn: Uncontrolled nesting depth in JSON parser
The Jawn parser before 1.6.1 is vulnerable to a denial of service attack via untrusted input.
Impact
A remote attacker who can submit JSON to any jawn-backed parse method can exhaust JVM heap and trigger java.lang.OutOfMemoryError. This is treated by Scala as a fatal error and not typically handled by scala.util.Try or cats.effect.IO.
Patches
Version 1.6.1 introduces a configurable nesting-depth limit (Parser#maxDepth, default 4096). Inputs deeper than the limit fail with a recoverable ParseException instead of exhausting heap.
Users who require deeper nesting may override maxDepth on a Parser subclass.
Workarounds
- Enforce an input size limit small enough that the resulting context stack cannot exhaust heap, (e.g. http4s
EntityLimiter). - Pre-scan untrusted input and reject documents whose maximum delimiter nesting exceeds a threshold before handing them to jawn.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.typelevel:jawn-parser_2.12 | < 1.7.0 | 1.7.0 |
| Java / Kotlin (Maven) | org.typelevel:jawn-parser_2.13 | < 1.7.0 | 1.7.0 |
| Java / Kotlin (Maven) | org.typelevel:jawn-parser_3 | < 1.7.0 | 1.7.0 |
References
- https://github.com/typelevel/jawn/security/advisories/GHSA-cc4v-rvgp-2pf3
- https://github.com/typelevel/jawn/commit/191cb3a44e77f1afab439ee636bf66bdf3c54a04
- https://github.com/typelevel/jawn/commit/6219666641f9408498f85868f835e17bd8a72fed
- https://github.com/typelevel/jawn/commit/93ac93e9c992c11b4c03d5455d8551f9fb24da1b
- https://github.com/typelevel/jawn/commit/f6ace7e0db715de1a8c4618bed9378333a5c2214
- https://github.com/typelevel/jawn
- https://github.com/typelevel/jawn/releases/tag/v1.7.0
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-770- Platform
- Java / Kotlin (Maven)
- Package
org.typelevel:jawn-parser_2.12, org.typelevel:jawn-parser_2.13, org.typelevel:jawn-parser_3- Disclosed
- 23.09.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-cc4v-rvgp-2pf3 - CC BY 4.0
Vulnerability history: org.typelevel:jawn-parser_2.13
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 01.2022 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 1
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 2
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