CVE-2026-61814: Typelevel Jawn AsyncParser quadratic parsing effort denial of service

CVE-2026-61814 · Severity: high · CVSS 7.5 · Published 2026-09-23

Jawn is a widely-used JSON parsing library. Its AsyncParser component suffers from an algorithmic flaw that causes it to perform quadratic (O(n²)) work when processing large JSON tokens split across many small network chunks. An attacker who can send malicious JSON input with controlled chunk sizes can exhaust CPU resources, causing a denial-of-service condition in any application using AsyncParser for untrusted data.

Technologies: org.typelevel:jawn-parser_2.12 (Maven), org.typelevel:jawn-parser_2.13 (Maven), org.typelevel:jawn-parser_3 (Maven). Vendors: Maven.

Quick answers

Is CVE-2026-61814 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-61814 being exploited in the wild.
How severe is CVE-2026-61814?
High severity, with a CVSS score of 7.5, published 23 September 2026.
Which products and versions are affected?
org.typelevel:jawn-parser_2.12 (Maven) <= 1.6.0, ECOSYSTEM:introduced=0,fixed=1.7.0; org.typelevel:jawn-parser_2.13 (Maven) <= 1.6.0, ECOSYSTEM:introduced=0,fixed=1.7.0; org.typelevel:jawn-parser_3 (Maven) <= 1.6.0, ECOSYSTEM:introduced=0,fixed=1.7.0; Typelevel Jawn ≤ 1.6.0.
Is there a fix for CVE-2026-61814?
Yes. org.typelevel:jawn-parser_2.12 (Maven): upgrade to 1.7.0 or later; org.typelevel:jawn-parser_2.13 (Maven): upgrade to 1.7.0 or later; org.typelevel:jawn-parser_3 (Maven): upgrade to 1.7.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-61814 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-61814?
Check whether you run org.typelevel:jawn-parser_2.12 (Maven), org.typelevel:jawn-parser_2.13 (Maven), org.typelevel:jawn-parser_3 (Maven) or one of the others listed 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

  • org.typelevel:jawn-parser_2.12 (Maven): upgrade to 1.7.0 or later
    # set org.typelevel:jawn-parser_2.12 to 1.7.0 in your pom.xml or build.gradle
  • org.typelevel:jawn-parser_2.13 (Maven): upgrade to 1.7.0 or later
    # set org.typelevel:jawn-parser_2.13 to 1.7.0 in your pom.xml or build.gradle
  • org.typelevel:jawn-parser_3 (Maven): upgrade to 1.7.0 or later
    # set org.typelevel:jawn-parser_3 to 1.7.0 in your pom.xml or build.gradle

Technical details

The vulnerability is an algorithmic complexity flaw (CWE-407) in the AsyncParser component of Jawn. When a single JSON token arrives fragmented across many small network chunks, each call to the `absorb()` method rescans the incomplete token from the beginning rather than continuing from where the previous chunk left off, resulting in quadratic time complexity O(n²) with respect to token length. An attacker with the ability to control network transmission chunk sizes—or any network-accessible application parsing untrusted JSON—can trigger this behavior. The attack requires no authentication or user interaction; an unauthenticated remote attacker can send crafted JSON payloads to exhaust CPU and cause denial of service. The vulnerability was fixed in jawn-parser version 1.7.0.

Affected products

  • Typelevel Jawn ≤ 1.6.0

Identifiers

  • CVE-2026-61814
  • GHSA-w4cm-gvhj-cgw6

Timeline

  • 2026-06-24: disclosed
  • 2026-06-24: patched: Fixed in version 1.7.0
  • 2026-09-23: advisory

References

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