Medium [CVE-2026-54902] Use-After-Free in Oj::Parser SAJ Long Key Callback
This medium-severity Red Hat Linux advisory covers CVE-2026-54902.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
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.
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.
Is CVE-2026-54902 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-54902 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-2026-54902?
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 14 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 14 days ago·verify at source
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