CVE-2026-54902 Details
Description
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.
A use-after-free vulnerability has been identified in the Oj gem, specifically in the JSON parser's SAJ mode, prior to version 3.17.2. The issue arises because the parser does not safeguard cached object keys of 35 bytes or more from being garbage collected. This flaw allows a Ruby garbage collection callback, triggered during the processing of a hash's end, to reclaim the key string while the C parser still references it. Accessing the freed string value leads to a segmentation fault, with the crash evidence indicating control over the memory that was freed. Short keys are not affected as they are stored safely on the C stack.
Users should upgrade to Oj version 3.17.2 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 1, 2026CISA-ADP
Assessed Jul 1, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/ohler55/oj/security/advisories/GHSA-m578-w5vf-rfcm | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/ohler55/oj/security/advisories/GHSA-m578-w5vf-rfcm | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-416 | Use After Free | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Oj | < 3.17.2 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 1, 2026 | CVE Modified | CISA-ADP |
| Jul 1, 2026 | New CVE Received | [email protected] |