# Apache OpenNLP AbstractModelReader has an OOM Denial of Service via Unbounded Array Allocation

Advisory record · `GHSA-659w-93r5-9j6m`

- **Identifiers:** `GHSA-659w-93r5-9j6m` · `CVE-2026-42440`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **Weakness (CWE):** [CWE-770](https://cwe.mitre.org/data/definitions/770.html) · [CWE-789](https://cwe.mitre.org/data/definitions/789.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 4 May 2026
- **Updated:** 4 Nov 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 4 May 2026, 18:30 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `org.apache.opennlp:opennlp-tools` (Maven): affected `>=2.0.0, <2.5.9 || >=3.0.0-M1, <3.0.0-M3 || <1.9.5`; fixed in `2.5.9`, `3.0.0-M3`, `1.9.5`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Apache OpenNLP opennlp-tools (Maven) versions before 2.5.9, and versions from 3.0.0-M1 before 3.0.0-M3, are affected. A crafted binary model file can set a count field so that the library attempts an oversized array allocation, causing an out-of-memory error that crashes any JVM loading the file. Users should upgrade to 2.5.9 or 3.0.0-M3, and until then should avoid loading model files from untrusted sources.

Written 2 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** 0.0060, the 49th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 4 May 2026, 18:30 UTC: [Confirmed by GitHub Advisory Database](https://github.com/advisories/GHSA-659w-93r5-9j6m)
- 31 Oct 2026, 14:17 UTC: First seen by agentprime
- 31 Oct 2026, 14:17 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-659w-93r5-9j6m)

## Sources

- [GitHub Advisory Database: GHSA-659w-93r5-9j6m](https://github.com/advisories/GHSA-659w-93r5-9j6m)
- [OSV: GHSA-659w-93r5-9j6m](https://osv.dev/vulnerability/GHSA-659w-93r5-9j6m)
- <https://nvd.nist.gov/vuln/detail/CVE-2026-42440>
- <https://github.com/apache/opennlp/pull/1198>
- <https://github.com/apache/opennlp/commit/96a073f693f3a0ded808a475f7d7773c072bb8a1>
- <https://github.com/apache/opennlp/commit/fc9824a97709470353add08e44cf15dc08677094>
- <https://access.redhat.com/security/cve/CVE-2026-42440>
- <https://bugzilla.redhat.com/show_bug.cgi?id=2466494>
- <https://github.com/apache/opennlp>
- <https://github.com/apache/opennlp/blob/9a0a05466b3e46567e7999272ff72ee37b42976b/SECURITY.md?plain=1#L118>
- <https://github.com/apache/opennlp/releases/tag/opennlp-1.9.5>
- <https://github.com/apache/opennlp/releases/tag/opennlp-2.5.9>
- <https://github.com/apache/opennlp/releases/tag/opennlp-3.0.0-M3>
- <https://lists.apache.org/thread/s8xlkx1gqbxfsq48py5h6jphjvgqp1jo>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-659w-93r5-9j6m>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-659w-93r5-9j6m/>. Everything for agents: <https://agentprime.io/llms.txt>.