CVE-2026-54902
MediumCVSS 6.3Exploitation Probability (EPSS)
Low risk17th percentile — higher than 17% of all known CVEs
Summary
The Oj (Optimized JSON) library for Ruby prior to version 3.17.2 has a Use-After-Free vulnerability in SAJ mode. The Oj::Parser does not protect cached object keys (≥35 bytes) from garbage collection, and a Ruby callback in hash_end can free the key memory while the C parser still holds a pointer. This causes a segfault, confirmed by RIP pointing to address 0x4242.
Risk Assessment
An attacker can exploit this vulnerability to cause application crashes (segfault) or potentially achieve remote code execution if they control the freed memory content. The risk includes service disruption and system integrity compromise.
Recommendation
Immediately update the Oj gem to version 3.17.2 or later. If an update is not possible, avoid using SAJ mode with callbacks that may trigger garbage collection.
Original NVD description (English source)
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to version 3.17.2, is vulnerable to Use-After-Free when in SAJ mode. The Oj::Parser does not protect cached object keys (≥ 35 bytes) from garbage collection, and a Ruby callback that triggers GC inside hash_end can cause the key string to be reclaimed while the C parser still holds a pointer to it. The subsequent access to the freed string VALUE results in a segfault, confirmed by an RIP pointing to address 0x4242 (a canary-style pattern suggesting control over the freed memory's content). This issue has been fixed in version 3.17.2.