Process crash via callback-driven input mutation
Published Jun 30, 2026 · Updated Jun 30, 2026
Heap use-after-free in Oj before 3.17.2 allows local users to crash a Ruby process by mutating parsed JSON from a SAJ callback. Oj::Parser#parse retains a raw pointer to the Ruby string buffer while a SAJ or SAJ2 callback can resize that string, free the buffer, and leave the parser reading dangling memory. Reachability requires a callback that can resize the same input string during parsing; the published impact is limited to process availability.
Summary
What happened
Heap use-after-free in Oj before 3.17.2 allows local users to crash a Ruby process by mutating parsed JSON from a SAJ callback. Oj::Parser#parse retains a raw pointer to the Ruby string buffer while a SAJ or SAJ2 callback can resize that string, free the buffer, and leave the parser reading dangling memory. Reachability requires a callback that can resize the same input string during parsing; the published impact is limited to process availability.
The record
- CVE
- CVE-2026-54898
- Published
- Jun 30, 2026
- Updated
- Jun 30, 2026
- Vendor
- Peter Ohler
- Product
- Oj
- Classifications
- CWE-416, T1499.004
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 30, 2026CVE publishedPublication date reported by the CVE source.
- Jun 30, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.17.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Upstream SAJ input-mutation reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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