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+---
+gem: json
+cve: 2026-54696
+ghsa: x2f5-4prf-w687
+url: https://nvd.nist.gov/vuln/detail/CVE-2026-54696
+title: JSON generator heap buffer overflow when streaming to an IO
+date: 2026-06-30
+description: |
+  Ruby JSON is a JSON implementation for Ruby. Versions 2.9.0 through
+  2.19.8 are vulnerable to heap buffer overflow when the JSON generator
+  is provided with an oversized streamed object.
+
+  When streaming to an IO JSON.dump(obj, io) and JSON::State#generate(obj, io)
+  can write past the internal JSON generator buffer when a streamed
+  object contains an attacker-controlled string near 16 KB. Exploitation
+  would result in a reliable process crash/denial of service.
+
+  This was triaged on HackerOne as report #3785370.
+  The issue was confirmed there and I was asked to open it here.
+
+  This issue has been fixed in version 2.19.9.
+cvss_v3: 3.7
+unaffected_versions:
+  - "< 2.9.0"
+patched_versions:
+  - ">= 2.19.9"
+related:
+  url:
+    - https://nvd.nist.gov/vuln/detail/CVE-2026-54696
+    - https://rubygems.org/gems/json/versions/2.19.9
+    - https://github.com/ruby/json/releases/tag/v2.19.9
+    - https://github.com/ruby/json/blob/master/CHANGES.md#2026-06-11-2199
+    - https://hackerone.com/reports/3785370
+    - https://github.com/ruby/json/security/advisories/GHSA-x2f5-4prf-w687
+notes: |
+  - Got 2.19.9 and date from nvd.nist.gov web site.