CVE-2026-67211: OOM Denial of Service via Unbounded Map Pre-Sizing in Apache OpenNLP SymSpellModelSerializer Versions Affecte

This month

HIGH 7.5REMOTEWATCHLISTDOWNGRADE

CVE-2026-67211 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 Map Pre-Sizing in Apache OpenNLP SymSpellModelSerializer Versions Affected: - 3.0.0-M4 - 3.0.0-M5 (The opennlp-spellcheck extension was introduced in 3.0.0-M4. Releases 1.x and 2.x do not contain the affected code.) Description: The SymSpellModelSerializer.create() method reads two 32-bit signed integer count fields (unigramCount and bigramCount) from a binary SymSpell model stream and passes each value d

Why this priority

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

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-789
Published	2026-09-11
Last modified	2026-09-16

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

Last updated 2026-09-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-11 18:16 UTCPublished CVE record published
2026-09-16 14:04 UTCUpdated Record last modified

apache opennlp DOWNGRADE

Affected: 3.0.0 m4 · 3.0.0 m5

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.0.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.0.0 (Debian / Ubuntu)

apt-cache madison opennlp sudo apt install opennlp=<VERSION_BEFORE_3.0.0> sudo apt-mark hold opennlp

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list opennlp sudo dnf downgrade opennlp-<VERSION_BEFORE_3.0.0> sudo dnf versionlock add opennlp

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2026-67211?

opennlp: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-67211 being exploited?

CVE-2026-67211 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-2026-67211 affect?

CVE-2026-67211 affects opennlp. Severity is high (CVSS 7.5). OOM Denial of Service via Unbounded Map Pre-Sizing in Apache OpenNLP SymSpellModelSerializer Versions Affected: - 3.0.0-M4 - 3.0.0-M5 (The opennlp-spellcheck extension was introduced in 3.0.0-M4. Releases 1.x and 2.x do not contain the

How urgent is CVE-2026-67211?

Priority 50/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

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CVE-2026-42440 HIGH 7.5 UPGRADE OOM Denial of Service via Unbounded Array Allocation in Apache OpenNLP AbstractModelReader Versions Affected
CVE-2026-43825 HIGH 7.3 DOWNGRADE Untrusted Java Deserialization in Apache OpenNLP SvmDoccatModel Versions Affected: before 3.0.0-M4 (libsvm
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References

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