CVE-2026-63317
Description
A flaw was found in Apache OpenNLP. This vulnerability allows an attacker to achieve arbitrary class instantiation by providing a specially crafted XML feature generator descriptor within a model archive or by supplying untrusted format names. While not direct remote code execution, successful exploitation could lead to arbitrary code execution if a class with malicious side effects is present on the classpath, potentially allowing an attacker to execute unauthorized commands or access sensitive information.
Statement
Red Hat products ship Apache OpenNLP opennlp-tools as a transitive dependency. The vulnerability allows arbitrary class instantiation via crafted XML feature generator descriptors in model archives, but exploitation requires both a malicious model file and a gadget class on the classpath. Red Hat OpenShift AI (TrustyAI) bundles opennlp-tools but only uses TokenizerModel and SentenceModel for text tokenization — these model types do not contain XML feature generator descriptors and do not invoke the vulnerable GeneratorFactory code path. EAP XP bundles opennlp-tools via Apache Lucene, where the vulnerable code path is reachable through POS tagger and NER model loading, but model files are administrator-configured and not user-supplied.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.8 | N/A | 5.6 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | High | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
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