CVE-2026-42440: OOM Denial of Service via Unbounded Array Allocation in Apache OpenNLP AbstractModelReader Versions Affected

Q: How do I fix CVE-2026-42440?

opennlp: upgrade to 2.5.9. Exact commands for each OS are on this page.

Q: Is CVE-2026-42440 being exploited?

CVE-2026-42440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-42440 affect?

CVE-2026-42440 affects opennlp. Severity is high (CVSS 7.5). OOM Denial of Service via Unbounded Array Allocation in Apache OpenNLP AbstractModelReader Versions Affected: before 1.9.5 before 2.5.9 before 3.0.0-M3 Description: The AbstractModelReader methods getOutcomes(), getOutcomePatterns(

Q: How urgent is CVE-2026-42440?

Priority 48/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADE

CVE-2026-42440 is a high-severity flaw (CVSS 7.5) affecting opennlp. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OOM Denial of Service via Unbounded Array Allocation in Apache OpenNLP AbstractModelReader Versions Affected: before 1.9.5 before 2.5.9 before 3.0.0-M3 Description: The AbstractModelReader methods getOutcomes(), getOutcomePatterns(), and getPredicates() each read a 32-bit signed integer count field from a binary model stream and pass that value directly to an array allocation (new String[numOutcomes], new int[numOCTypes][], new String[NU

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-789, CWE-770
Published	2026-05-04
Last modified	2026-10-26

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-04 17:16 UTCPublished CVE record published
2026-10-26 19:10 UTCUpdated Record last modified

apache opennlp UPGRADE

Affected: < 2.5.9 · 3.0.0 m1 · 3.0.0 m2

Fixed in: 2.5.9

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy opennlp || rpm -q opennlp || opennlp --version

2. UPGRADE to 2.5.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade opennlp

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opennlp

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-42440?

opennlp: upgrade to 2.5.9. Exact commands for each OS are on this page.

Is CVE-2026-42440 being exploited?

CVE-2026-42440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-42440 affect?

CVE-2026-42440 affects opennlp. Severity is high (CVSS 7.5). OOM Denial of Service via Unbounded Array Allocation in Apache OpenNLP AbstractModelReader Versions Affected: before 1.9.5 before 2.5.9 before 3.0.0-M3 Description: The AbstractModelReader methods getOutcomes(), getOutcomePatterns(

How urgent is CVE-2026-42440?

Priority 48/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Related CVEs

CVE-2026-42027 CRITICAL 9.8 UPGRADE Arbitrary Class Instantiation via Model Manifest in Apache OpenNLP ExtensionLoader Versions Affected: bef
CVE-2026-40682 CRITICAL 9.1 UPGRADE XML External Entity (XXE) via Unsanitized Dictionary Parsing in Apache OpenNLP DictionaryEntryPersistor Vers
CVE-2026-43825 HIGH 7.3 DOWNGRADE Untrusted Java Deserialization in Apache OpenNLP SvmDoccatModel Versions Affected: before 3.0.0-M4 (libsvm
CVE-2026-63317 MEDIUM 5.6 UPGRADE Arbitrary Class Instantiation via XML Feature Generator Descriptor and Format Name in Apache OpenNLP Versions
CVE-2026-82617 CRITICAL 9.8 UPGRADE The two built-in name-finder patterns exposed by opennlp.tools.namefind.RegexNameFinderFactory - DEFAULT_REGEX

References

← Back to latest CVEs