Ruby process crash via unchecked indent writes
Published Jun 30, 2026 · Updated Jun 30, 2026
Heap buffer overflow in Oj.dump Exception serialization in Oj before 3.17.2 allows local users to crash a Ruby process via a large indent. In ext/oj/dump.h, fill_indent repeatedly writes indent times depth bytes with memset while the output allocation excludes indentation overhead. Exploitation requires object mode and an application path that accepts an attacker-influenced indent; the demonstrated overflow corrupts adjacent heap memory.
Summary
What happened
Heap buffer overflow in Oj.dump Exception serialization in Oj before 3.17.2 allows local users to crash a Ruby process via a large indent. In ext/oj/dump.h, fill_indent repeatedly writes indent times depth bytes with memset while the output allocation excludes indentation overhead. Exploitation requires object mode and an application path that accepts an attacker-influenced indent; the demonstrated overflow corrupts adjacent heap memory.
The record
- CVE
- CVE-2026-54896
- Published
- Jun 30, 2026
- Updated
- Jun 30, 2026
- Vendor
- Peter Ohler
- Product
- Oj
- Classifications
- CWE-122, 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.
Weakness, pattern, technique
Public exploit references
- Large-indent Exception serialization reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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