CVE-2026-54897 is a high-severity use after free vulnerability in oj (rubygems), affecting versions < 3.17.2. It is fixed in 3.17.3.
Summary Oj::Doc iterators (eachvalue, eachchild, eachleaf) are vulnerable to a heap use-after-free. When a Ruby block yielded during iteration calls doc.close or d.close, the document's heap memory is freed while the C iterator is still running. When control returns from the block, the iterator reads from the freed region, producing a use-after-free accessible from pure Ruby. Version Software: oj gem Affected: all versions with ext/oj/fast.c Latest tested: 3.17.1 (confirmed present) Details The iterators in ext/oj/fast.c follow the pattern: rbyield can invoke arbitrary Ruby code, including calling close() on the Doc or any child node, which calls rubysizedxfree on the backing buffer. On return, the C code reads cur->next from the freed region. All three iterators are affected. ASAN report (each_child variant): All three iterators trigger the same freed region (fd shadow bytes): Reproduce
Memory is accessed after it has been freed, leading to undefined behavior in native code. Typical impact: memory corruption, crash, or potential code execution.
rubygems
oj (< 3.17.2)oj → 3.17.3 (rubygems)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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CVE-2026-54897 is a high-severity use after free vulnerability in oj (rubygems), affecting versions < 3.17.2. It is fixed in 3.17.3. Memory is accessed after it has been freed, leading to undefined behavior in native code.
oj (rubygems) versions < 3.17.2 is affected.
Yes. CVE-2026-54897 is fixed in 3.17.3. Upgrade to this version or later.
Whether CVE-2026-54897 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade oj to 3.17.3 or later.