High [CVE-2026-54897] Use-After-Free in Oj::Doc Iterators via reentrant close
This high-severity Red Hat Linux advisory covers CVE-2026-54897.
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VulniPulse record published Record updated
Summary
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to 3.17.2, Oj::Doc iterators (each_value, each_child, each_leaf) were 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.
This issue has been fixed in version 3.17.2. A flaw was found in Oj (Optimized JSON), a Ruby gem for parsing JSON.
An attacker could exploit this when a Ruby code block, executed during iteration, prematurely closes the document. This action frees the document's memory while the iterator is still active, leading to an attempt to access freed memory and potentially causing application instability or other unpredictable behavior.
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: Important — CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-364.
Is CVE-2026-54897 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-54897 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-54897?
Upgrade to a fixed release named by Red Hat:
- 3.17.2
Confirm against the vendor advisory before you patch.
- < 3.17.2
Official advisory · high-confidence parse· fetched 11 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 interim mitigations or workarounds not captured here. Review it before change work.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
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