Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%

CVE-2026-67211— Apache OpenNLP: OOM DoS via Unbounded Array Allocation in SymSpellModelSerializer

Quick assessment

Affected
Apache Software Foundation Apache OpenNLP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Apache OpenNLP是美国Apache基金会的一款服务端软件产品。 Apache OpenNLP 3.0.0-M4版本和3.0.0-M5版本存在资源管理错误漏洞,该漏洞源于SymSpellModelSerializer.create()方法从二进制SymSpell模型流中读取的unigramCount和bigramCount计数字段仅验证非负而未设置上限,特制的.bin模型文件将计数字段设置为较大值会导致映射预分配超大容量并触发内存溢出,可能导致拒绝服务。

AI Predicted 5.5 Difficulty: Easy EPSS 0.74% · P55

Affected Version Matrix 1

VendorProduct Version RangeStatus
Apache Software Foundation Apache OpenNLP 3.0.0-M4< 3.0.0-M6 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-67211

Vulnerability Information

Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Apache OpenNLP: OOM DoS via Unbounded Array Allocation in SymSpellModelSerializer
Source: CVE Program / CVE List V5
Vulnerability Description
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 directly to LinkedHashMap.newLinkedHashMap() after validating only that it is non-negative. No upper bound is applied, so the count is fully attacker-controlled when the model file originates from an untrusted source. A crafted .bin model file in which either count field is set to Integer.MAX_VALUE (or any value large enough to exhaust the available heap) causes the map to be pre-sized to a capacity of 2^30 entries. The oversized backing array is allocated on the first put() into that map, requesting 4–8 GB depending on whether compressed oops are in effect, and the load fails with an OutOfMemoryError. Because the count fields sit immediately after a fixed-size header (magic, format version, three UTF strings, the configuration fields, and the edit-distance identifier) the attacker pays no meaningful size cost to weaponize a payload: a file of well under 100 bytes plus a single real entry is sufficient to crash a JVM that loads it. Any code path that deserializes a SymSpell model is affected, including SymSpellModels.deserialize(InputStream), SymSpellModels.fromBytes(byte[]), classpath model loading via SymSpellModelResolver.resolveByLanguage(String), the CorrectTextTool command-line tool, and model-archive loading through the registered ArtifactSerializer. The opennlp-spellcheck extension ships in the official OpenNLP binary distribution. The practical impact is denial of service against processes that load SymSpell model files from untrusted or semi-trusted origins. Mitigation: - 3.x users should upgrade to 3.0.0-M6. Note: The fix applies an upper bound to both count fields, checked before the map is pre-sized; counts that are negative or exceed the bound cause an IOException to be thrown and the read to fail fast with no large allocation. The bound is the existing AbstractModelReader.MAX_ENTRIES limit introduced earlie, which the current change promotes to public visibility so that serializers implementing their own binary format can share it. The default bound is 10,000,000, which is well above the entry counts of legitimate SymSpell dictionaries but far below any value that would threaten heap exhaustion. Deployments that legitimately need to load larger dictionaries can raise the limit at JVM startup by setting the OPENNLP_MAX_ENTRIES system property to the desired positive integer (e.g. -DOPENNLP_MAX_ENTRIES=50000000); invalid or non-positive values fall back to the default. Note that this property is shared with the model-reader limit and raising it relaxes both. Users who cannot upgrade immediately should treat all SymSpell .bin model files as untrusted input unless their provenance is verified, and should avoid loading models supplied by end users or fetched from third-party repositories without integrity checks.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
未经控制的内存分配
Source: CVE Program / CVE List V5
Vulnerability Title
Apache OpenNLP 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Apache OpenNLP是美国Apache基金会的一款服务端软件产品。 Apache OpenNLP 3.0.0-M4版本和3.0.0-M5版本存在资源管理错误漏洞,该漏洞源于SymSpellModelSerializer.create()方法从二进制SymSpell模型流中读取的unigramCount和bigramCount计数字段仅验证非负而未设置上限,特制的.bin模型文件将计数字段设置为较大值会导致映射预分配超大容量并触发内存溢出,可能导致拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Apache Software Foundation Apache OpenNLP 3.0.0-M4 ~ 3.0.0-M6 -

II. Public POCs for CVE-2026-67211

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-67211

请登录查看更多情报信息。

Mailing List Discussions for CVE-2026-67211 (1)

IV. Related Vulnerabilities