Medium [CVE-2026-54899] Use-After-Free in parser symbol key cache toggle
This medium-severity Red Hat Linux advisory covers CVE-2026-54899.
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Summary
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to version 3.17.2, disabling symbol_keys on a reused Oj::Parser instance triggers a heap use-after-free.
When symbol_keys is toggled from true to false, opt_symbol_keys_set frees the internal key cache (cache_free) but does not clear the pointer. The next parse call reads from the freed cache via cache_intern, producing a use-after-free.
This issue has been fixed in version 3.17.2. A flaw was found in Oj (Optimized JSON), a Ruby gem for parsing JSON.
This happens because the internal key cache is freed but its pointer is not cleared, allowing subsequent parse operations to read from freed memory. This can lead to unpredictable application behavior, crashes, or potentially arbitrary code execution.
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 — CVSS 6.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H). Weakness: CWE-825.
Is CVE-2026-54899 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-54899 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-2026-54899?
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 12 days ago·verify at source
Mitigation checklist
- Upgrade the oj Ruby gem to version 3.17.2 or later.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
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