Process crash via unbounded model array allocation
Published May 4, 2026 · Updated May 4, 2026
Denial of service in Apache OpenNLP before 2.5.9 and before 3.0.0-M3 allows attackers to crash a model-loading JVM via a crafted .bin file. AbstractModelReader methods read attacker-controlled 32-bit counts and allocate outcome, pattern, or predicate arrays without first rejecting excessive values, causing an OutOfMemoryError before the model data is consumed. Exploitation requires an embedding application or command-line workflow to load an untrusted model, and the resulting availability loss is limited to the affected JVM process.
Summary
What happened
Denial of service in Apache OpenNLP before 2.5.9 and before 3.0.0-M3 allows attackers to crash a model-loading JVM via a crafted .bin file. AbstractModelReader methods read attacker-controlled 32-bit counts and allocate outcome, pattern, or predicate arrays without first rejecting excessive values, causing an OutOfMemoryError before the model data is consumed. Exploitation requires an embedding application or command-line workflow to load an untrusted model, and the resulting availability loss is limited to the affected JVM process.
The record
- CVE
- CVE-2026-42440
- Published
- May 4, 2026
- Updated
- May 4, 2026
- Vendor
- The Apache Software Foundation
- Product
- Apache OpenNLP
- Classifications
- CWE-770, CWE-789, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 4, 2026CVE publishedPublication date reported by the CVE source.
- May 4, 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=0 <2.5.9
- Affected versionversion=3.0 <3.0.0-M3
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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