Jawn: Uncontrolled nesting depth in JSON parser

Answer in brief

CVE-2026-59990 records a High severity (CVSS 7.5) vulnerability in Jawn: Uncontrolled nesting depth in JSON parser. The current sources do not mark it as known exploited. The current feed maps typelevel/jawn (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 23, 2026Updated Sep 23, 2026Source checked Sep 23, 2026First seen by HOL Sep 23, 2026Material review Sep 23, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps typelevel/jawn (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
typelevel/jawngeneric	<1.7.0	1.7.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for typelevel/jawn.
Review the reported fix. Update typelevel/jawn to 1.7.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 23, 2026

Sources and claim methodology

Upstream source description

Jawn is an open source JSON parser. Prior to 1.7.0, Jawn parse methods accept arbitrarily deep JSON array and object nesting without a depth limit, allowing a remote attacker who can submit untrusted JSON to grow parser contexts until the JVM heap is exhausted. The resulting java.lang.OutOfMemoryError is a fatal Scala error that is not ordinarily handled by scala.util.Try or cats.effect.IO, causing denial of service. This issue is fixed in version 1.7.0.

Quoted source text, attributed separately from HOL analysis.