CVE-2026-41849: Integer Overflow Denial of Service via SpEL String Multiplication in Spring Framework
HERMES THREAT SCORE & OPERATIONAL EXPOSURE
Target:Spring Expression Language (SpEL OpMultiply) — Spring Framework Hermes rates CVE-2026-41849 at 83 (HIGH). The `OpMultiply` operator in SpEL supports string repetition (e.g. `'payload' * 1000000000`). If user input is dynamically evaluated, integer overflow during memory pre-allocation causes sudden JVM heap saturation and immediate OutOfMemoryError, crashing the Spring Boot container.
HASS INFRASTRUCTURE & AGENTIC IMPACT POSTURE
Target:Dynamic Query APIs, Spring Batch Jobs & SpEL Template Evaluators Critical enterprise Java applications, microservice clusters, and CI/CD pipelines depend on strict memory and authorization boundaries. Vulnerabilities in core components like Spring Expression Language (SpEL OpMultiply) allow adversaries to break through sandbox isolation and compromise business-critical assets.
CVE-2026-41849: Integer Overflow Denial of Service via SpEL String Multiplication in Spring FrameworkVULNERABILITY
Software platform affected by security vulnerabilities and agentic attack patterns.
🔍 Why is this related? (Evidence & Provenance)
“Confirmed security vulnerability in Spring Framework documented in Hermes dossier.”
- [vulnerability_report]
- [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)
1. Technical Context & Affected Software Matrix
Section titled “1. Technical Context & Affected Software Matrix”The vulnerability CVE-2026-41849 resides in the Spring Expression Language (SpEL OpMultiply) subsystem of Spring Framework.
+-----------------------------------------------------------------------------------------+| JAVA RUNTIME ECOSYSTEM || || +---------------------------------------------------------------------------------+ || | APPLICATION & MICROSERVICE LAYER | || | Spring Boot / Quarkus / Micronaut / Web Applications / Custom JVM Services | || +---------------------------------------+-----------------------------------------+ || | || v || +---------------------------------------------------------------------------------+ || | AFFECTED SUBSYSTEM: Spring Expression Language (SpEL OpMultiply) | || | Root Flaw: Integer Overflow or Wraparound | || +---------------------------------------+-----------------------------------------+ || | || v || +---------------------------------------------------------------------------------+ || | OPERATING SYSTEM & CONTAINER ENGINE | || | Linux / Windows / Docker / Kubernetes Pod Sandboxes & Native Libraries | || +---------------------------------------------------------------------------------+ |+-----------------------------------------------------------------------------------------+Vulnerability Vector & Attack Mechanics
Section titled “Vulnerability Vector & Attack Mechanics”| Dimension | Specification |
|---|---|
| Vulnerability Identifier | CVE-2026-41849 |
| Component Affected | Spring Expression Language (SpEL OpMultiply) |
| Primary CWE | CWE-190 (Integer Overflow or Wraparound) |
| CVSS v3.1 Score & Vector | 7.5 (HIGH) — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| Attack Vector / Surface | AV:N (Unauthenticated, Scope Unchanged (S:U)) |
| Integrity Impact | None |
| Confidentiality Impact | None |
| Availability Impact | High (Total JVM Crash / Denial of Service) |
| Affected Releases | Spring Framework 5.3.0 through 5.3.48 (Branch 6.x and 7.x unaffected) |
| Recommended Safe Version | 5.3.49 |
2. Root Cause & Attack Vector Analysis
Section titled “2. Root Cause & Attack Vector Analysis”Vulnerability Anatomy
Section titled “Vulnerability Anatomy”The defect in CVE-2026-41849 is caused by integer overflow or wraparound within Spring Expression Language (SpEL OpMultiply).
When untrusted data or requests reach this component, the missing boundary validation or logic error triggers an unexpected state transition, as depicted in the sequence diagram below:
sequenceDiagram autonumber actor Attacker as Threat Actor / Malicious Client participant Service as Java Host / Gateway participant Component as Subsystem (Spring Expression Language (SpEL OpMultiply)) participant Target as JVM Memory / Host OS
Attacker->>Service: Dispatch crafted payload (Integer Overflow & Catastrophic Memory Allocation DoS) Service->>Component: Forward input to processing pipeline activate Component Note over Component: CWE-190: Validation failure / logic defect Component->>Target: Trigger uncontrolled condition (Confined to JVM Process & Container Sandbox) deactivate Component Target-->>Attacker: Exploit effect achieved (Integer Overflow & Catastrophic Memory Allocation DoS)3. Threat Hunting & Incident Detection
Section titled “3. Threat Hunting & Incident Detection”Deploy the following detection rules to monitor runtime behavior and identify exploitation attempts against CVE-2026-41849.
Sigma Rule (Process & Event Monitoring)
Section titled “Sigma Rule (Process & Event Monitoring)”title: Suspicious Activity Related to CVE-2026-41849 (Spring Expression Language (SpEL OpMultiply))id: cve-2026-41849-sigma-detectionstatus: experimentaldescription: Detects unusual execution patterns or anomalous errors matching CVE-2026-41849 exploitation.references: - https://nvd.nist.gov/vuln/detail/CVE-2026-41849 - https://hermes-codex.dev/cve/2026/cve-2026-41849/author: Hermes Codex Cyber Threat Intelligencedate: 2026-09-15logsource: category: process_creation product: linuxdetection: selection_parent: ParentImage|endswith: - '/java' selection_child: Image|endswith: - '/java' condition: selection_parent and selection_childfields: - CommandLine - Image - ParentCommandLinefalsepositives: - Legitimate administrative maintenance - Authorized automated deploymentslevel: hightags: - attack.execution - attack.initial_access - cve.cve-2026-41849Network Detection Signature (Suricata / Snort)
Section titled “Network Detection Signature (Suricata / Snort)”alert tcp any any -> $HOME_NET any (msg:"HERMES-CODEX - Potential CVE-2026-41849 Exploitation Pattern in Spring Expression Language (SpEL OpMultiply)"; flow:to_server,established; content:"|00|"; threshold:type limit, track by_src, count 5, seconds 60; classtype:attempted-admin; sid:2026418491; rev:1; metadata:cve CVE-2026-41849, hermes_threat_score 83;)YARA Memory & Artifact Rule
Section titled “YARA Memory & Artifact Rule”rule Hermes_CVE_2026_41849_Artifact { meta: description = "Identifies in-memory patterns and exploit strings associated with CVE-2026-41849" author = "Hermes Codex Research" cve = "CVE-2026-41849" severity = "HIGH" date = "2026-09-15" strings: $fp1 = "Spring Expression Language (SpEL OpMultiply)" ascii wide $fp2 = "CWE-190" ascii wide $magic = "CVE-2026-41849" ascii wide condition: all of them}4. Remediation, Patching & Defensive Hardening
Section titled “4. Remediation, Patching & Defensive Hardening”-
Apply Official Vendor Security Patches: Upgrade your installation of Spring Framework to
5.3.49or newer immediately. -
Harden Network & Component Boundaries: Ensure that external clients cannot interact directly with untrusted internal endpoints. Place Java application runtimes behind strict reverse proxies or Web Application Firewalls (WAF).
-
Verify Security Configurations: Audit deployment configurations, JVM arguments, and security descriptors to ensure least-privilege principles are enforced across all runtime containers.