CVE-2026-93879: 
Linux Debian 脆弱性分析と緩和策

CVE-2026-93879 is a Denial of Service (DoS) vulnerability in Hibernate Validator caused by improper escaping of user-controlled data in Expression Language (EL) expressions. It affects Hibernate Validator starting with version 5.4.1 and impacts products built on it, including IBM Enterprise Build of Quarkus. The CVE was reserved and published on October 12, 2026, with a CVSS v3.1 base score of 7.5 (High) (Red Hat CVE, Red Hat Bugzilla).

The root cause is classified as CWE-400 (Uncontrolled Resource Consumption). Hibernate Validator fails to properly escape user-supplied data in constraint violation message parameters — specifically, unescaped {duplicates} message parameters are re-evaluated as Expression Language expressions during validation processing. An unauthenticated remote attacker can submit specially crafted input containing unescaped EL message parameters, causing the application to perform excessive EL re-evaluation, leading to resource exhaustion. No authentication or user interaction is required, and the attack is conducted over the network with low complexity (Red Hat Bugzilla, Red Hat CVE).

Successful exploitation results in a high availability impact — the targeted application becomes unresponsive due to excessive resource consumption, effectively causing a Denial of Service. There is no impact on confidentiality or integrity. Applications using Hibernate Validator for input validation (e.g., Jakarta EE or Quarkus-based services) that expose validation endpoints to untrusted input are at risk of complete service unavailability (Red Hat CVE, IBM Advisory).

No public proof-of-concept exploit code or in-the-wild exploitation has been reported for CVE-2026-93879 as of the available data. The vulnerability requires no privileges and no user interaction, making it trivially exploitable by any network-accessible attacker against vulnerable deployments. The CVE status remains "Reserved" with no CISA KEV catalog listing or known threat actor attribution at this time (Red Hat CVE, Red Hat Bugzilla).

1. Reconnaissance: Identify network-accessible applications using Hibernate Validator 5.4.1 or later (e.g., Quarkus-based REST APIs or Jakarta EE services) that perform bean validation on user-supplied input.
2. Craft malicious payload: Construct input containing unescaped EL message parameter syntax (e.g., ${...} or #{...} expressions embedded in fields subject to constraint validation) that will be passed into Hibernate Validator's message interpolation engine.
3. Submit crafted request: Send the malicious input via an HTTP request (e.g., POST body, query parameter, or form field) to any endpoint that triggers bean validation on the attacker-controlled data.
4. Trigger EL re-evaluation: The unescaped parameter causes Hibernate Validator to re-evaluate the user-supplied content as an EL expression during message interpolation, consuming excessive CPU and memory resources.
5. Achieve DoS: Repeated or sufficiently complex payloads cause the application to exhaust resources, resulting in unresponsiveness or crash (Red Hat Bugzilla, Red Hat CVE).

• Network: High volume of HTTP requests to validation-heavy endpoints (e.g., REST API POST endpoints) from a single or small set of source IPs containing unusual characters such as ${, #{, or } in request bodies or parameters.
• Logs: Application logs showing repeated or unusually slow constraint validation processing; EL evaluation errors or stack traces in application server logs (e.g., javax.el.ELException or similar).
• Process/Resource: Sudden spikes in CPU or heap memory usage by the Java application process coinciding with incoming requests; JVM garbage collection logs showing excessive GC pressure or out-of-memory events.
• Application: Increased response latency or timeouts on endpoints that perform bean validation; application health checks failing or returning 503 errors (Red Hat Bugzilla).

Patches have been issued via Red Hat Security Advisories RHSA-2026:83082 and RHSA-2026:83520 for Red Hat Build of Quarkus 3.33.4.1 and related products. IBM has also released a security bulletin addressing IBM Enterprise Build of Quarkus. Users should upgrade to a patched version of Hibernate Validator and the affected Quarkus distribution as soon as possible. As a workaround, restrict untrusted user input from reaching validation endpoints, or apply input sanitization to strip EL expression syntax before validation processing (Red Hat Advisory RHSA-2026:83082, IBM Advisory, Quarkus Blog).

Red Hat filed a Bugzilla entry with 68 CC'd users, indicating broad internal awareness across multiple product teams. IBM issued a security bulletin acknowledging the impact on IBM Enterprise Build of Quarkus. The Quarkus project published a release blog for version 3.33.4.1 addressing this and other vulnerabilities. No notable independent researcher commentary or significant social media discussion has been identified (Red Hat Bugzilla, IBM Advisory, Quarkus Blog).