High [CVE-2026-54903] Heap corruption and Denial of Service via integer overflow in JSON parsing
This high-severity Red Hat Linux advisory covers CVE-2026-54903.
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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.load is vulnerable to heap corruption when parsing a JSON string longer than 2 GB.
An integer overflow in buf_append_string (buf.h:61) converts the string length to a large negative size_t, causing memcpy to copy an astronomically large amount of data out of bounds. This crashes the process and can corrupt adjacent heap memory.
The issue has been fixed in version 3.17.2. A flaw was found in Oj, an Optimized JSON (JavaScript Object Notation) parser for Ruby.
This vulnerability allows a remote attacker to cause heap corruption and a denial of service (DoS) by providing a JSON string larger than 2 gigabytes (GB). An integer overflow occurs when processing the string length, leading to out-of-bounds memory access and a process crash.
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 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-787.
Is CVE-2026-54903 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-54903 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-2026-54903?
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 13 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 13 days ago·verify at source
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