Medium [CVE-2026-54898] Denial of Service via input string mutation during JSON parsing
This medium-severity Red Hat Linux advisory covers CVE-2026-54898.
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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. In versions prior to 3.17.2,Oj::Parser#parse is vulnerable to a heap use-after-free when a SAJ/SAJ2 callback mutates the input JSON string during parsing.
The C engine holds a raw const byte * pointer into the Ruby string's internal buffer. If a callback (e.g. hash_start) resizes the string — for example by calling String#replace with a longer value — Ruby reallocates the string buffer and frees the old one.
The C parser's pointer is left dangling; the next character read at parser.c:607 is a use-after-free. This issue has been fixed in version 3.17.2.
A flaw was found in Oj, a Ruby library designed for efficient JSON (JavaScript Object Notation) parsing. This action can lead to the program attempting to access memory that has already been freed, potentially causing the application to crash and resulting in a denial of service.
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:L/PR:N/UI:R/S:U/C:N/I:N/A:H). Weakness: CWE-825.
Is CVE-2026-54898 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-54898 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-2026-54898?
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
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 12 days ago·verify at source
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