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CVE-2026-54900

Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling

CVSS 6.3 MEDIUMEPSS 0.3%CWE-190CWE-787
Vexday Risk Score
13Low
SSVC decision (CISA)
Track
No exploitation signal → monitor
CVSS 6.3EPSS 0.3%KEV nãoPoC Nuclei Metasploit Patch
Lifecycle
30 Jun 2026Published on NVD
Recommendation: Monitor — no exploitation signal at the moment.
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Affected products
ohler55 · oj

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