CVE-2026-73635
Description
A flaw was found in Apache Struts. An unauthenticated remote client can exploit a vulnerability where the framework's localized-text caches grow without bound. This occurs when no fixed locale is configured, and the locale for text lookups is derived from the incoming request. This can lead to the exhaustion of Java heap memory, resulting in a Denial of Service (DoS) for other users.
Statement
An uncontrolled resource consumption flaw exists in the Apache Struts localized-text lookup caching mechanism. When no fixed application locale is configured, incoming HTTP request headers dynamically set the lookup locale, allowing the internal text cache to grow without bound. An unauthenticated remote attacker can exploit this by streaming requests with arbitrary, unique locale parameters, exhausting JVM heap space and causing a denial of service. The impact is limited to process availability.
Mitigation
Configure a fixed default locale in `struts.xml` by setting the `struts.locale` property (e.g., `<constant name="struts.locale" value="en_US" />`). Alternatively, configure an API gateway or web application firewall (WAF) to sanitize or strip non-standard `Accept-Language` headers before forwarding traffic to the application.
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 | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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