CVE-2026-54696CWE-122CWE-131CWE-787

Ruby JSON: JSON generator heap buffer overflow when streaming to an IO

Low · published June 30, 2026

CVSS v3.1
3.7
EPSS
0%
Percentile
31.0
In the wild
Unconfirmed
What it is

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 issue has been fixed in version 2.19.9.

The record
Technical detail
CVSS v3.1
3.7 · LOW
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00382 · 31.0th percentile
Weaknesses
CWE-122 · Heap-based Buffer Overflow; CWE-131 · Incorrect Calculation of Buffer Size; CWE-787 · Out-of-bounds Write
Published
2026-06-30T22:05Z
EPSS history
Timeline
  • 30 JUN 22:05Z
    Ruby JSON: JSON generator heap buffer overflow when streaming to an IO
    cvelistv5