Process crash via unmarked parser class references
Published Jun 30, 2026 · Updated Jul 1, 2026
Use-after-free in Oj before 3.17.2 allows remote attackers to crash a Ruby process via parser class references reclaimed during garbage collection. The parser_mark callback omits d->array_class and d->hash_class from rb_gc_mark, so close_array_class later passes a reclaimed Ruby VALUE to rb_funcallv. Exploitation requires usual mode, a configured array_class or hash_class, garbage collection between assignment and parsing, and application exposure of the parse path.
Summary
What happened
Use-after-free in Oj before 3.17.2 allows remote attackers to crash a Ruby process via parser class references reclaimed during garbage collection. The parser_mark callback omits d->array_class and d->hash_class from rb_gc_mark, so close_array_class later passes a reclaimed Ruby VALUE to rb_funcallv. Exploitation requires usual mode, a configured array_class or hash_class, garbage collection between assignment and parsing, and application exposure of the parse path.
The record
- CVE
- CVE-2026-54901
- Published
- Jun 30, 2026
- Updated
- Jul 1, 2026
- Vendor
- Peter Ohler
- Product
- Oj
- Classifications
- CWE-416, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 30, 2026CVE publishedPublication date reported by the CVE source.
- Jul 1, 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
- GHSA-vwm4-62gf-x745 parser crash reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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