Low severity · published Jun 30, 2026
CVE-2026-54696
Ruby JSON: JSON generator heap buffer overflow when streaming to an IO
3.7
CVSS
0.4%
EPSS
No
On KEV
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 issue has been fixed in version 2.19.9.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 35% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JS
json · ruby
>= 2.9.0, < 2.19.9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54696
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-54696
github.com
https://github.com/ruby/json/releases/tag/v2.19.9
github.com
https://github.com/ruby/json/security/advisories/GHSA-x2f5-4prf-w687
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