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

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Summary

CVECVE-2026-54696
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-30 23:17:28 UTC
Updated2026-07-02 17:54:15 UTC
DescriptionRuby 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.

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.003010000 probability, percentile 0.218530000 (date 2026-07-03)

Problem Types: CWE-122 | CWE-131 | CWE-787 | CWE-122 CWE-122: Heap-based Buffer Overflow | CWE-131 CWE-131: Incorrect Calculation of Buffer Size | CWE-787 CWE-787: Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Ruby Json affected >= 2.9.0, < 2.19.9 Not specified

References

ReferenceSourceLinkTags
github.com/ruby/json/releases/tag/v2.19.9 [email protected] github.com
github.com/ruby/json/security/advisories/GHSA-x2f5-4prf-w687 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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