Medium [CVE-2026-54901] Use-After-Free in Oj::Parser array_class/hash_class GC Marking
This medium-severity Red Hat Linux advisory covers CVE-2026-54901.
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Summary
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free.
If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault.
This issue has been fixed in version 3.17.2. Red Hat's only product shipping the Oj Ruby gem (Compliance Backend) already includes version 3.17.3, which contains the fix for this vulnerability.
No Red Hat products are affected. Red Hat severity: Moderate.
- < 3.17.2
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation
Upgrade to a fixed release: 3.17.2. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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