Overview
CVE-2017-8046 describes a remote code execution risk in servers running Spring Data REST with older patch handling and deserialization behavior. Malicious PATCH requests could carry specially crafted JSON data that, when deserialized, triggers gadget chains in the Java runtime, allowing arbitrary Java code execution on the server. This is a security misconfiguration tied to improper handling of untrusted input (CWE-20). The issue affected Spring Data REST versions prior to 2.6.9 (Ingalls SR9) and prior to 3.0.1 (Kay SR1), and Spring Boot versions prior to 1.5.9 or 2.0 M6, making servers that exposed PATCH endpoints vulnerable to remote code execution via crafted payloads. In practice, attackers could exploit this by sending a PATCH request that triggers unsafe deserialization during resource updates. This guide references CVE-2017-8046 specifically and outlines concrete upgrade paths and hardening steps for Spring Boot applications.
In real-world Spring Boot deployments, security misconfigurations around deserialization often show up as exposed PATCH endpoints that accept untrusted JSON and rely on polymorphic deserialization by Jackson or related libraries. The vulnerability is mitigated by upgrading to patched library versions (Ingalls SR9, Kay SR1) and Spring Boot releases that disable or safely constrain deserialization pathways, along with broader hardening like restricting HTTP methods and avoiding polymorphic deserialization of untrusted data. The remediation also aligns with CWE-20 by ensuring input validation and trusted deserialization behavior.
This guide focuses on concrete upgrades and code-level hardening applicable to Spring Boot applications, so teams can reduce exposure to CVE-2017-8046 while maintaining legitimate update semantics for PATCH operations.
Affected Versions
Spring Data REST: before 2.6.9 (Ingalls SR9), before 3.0.1 (Kay SR1); Spring Boot: before 1.5.9, before 2.0 M6
Code Fix Example
Spring Boot API Security Remediation
Vulnerable:
@RestController
public class VulnerableController {
@PatchMapping("/resources/{id}")
public Resource patch(@PathVariable Long id, @RequestBody String payload) throws IOException {
ObjectMapper mapper = new ObjectMapper();
// Vulnerable: enabling polymorphic typing for untrusted input
mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
Resource res = mapper.readValue(payload, Resource.class);
// apply patch logic (simplified)
return res;
}
}
Fixed:
@RestController
public class FixedController {
@PatchMapping("/resources/{id}")
public Resource patch(@PathVariable Long id, @RequestBody PatchDTO patch) {
// Safe: use explicit DTO and avoid polymorphic/deserialization of untrusted data
Resource existing = repository.findById(id).orElseThrow(() -> new ResourceNotFoundException(id));
if (patch.getName() != null) existing.setName(patch.getName());
if (patch.getDescription() != null) existing.setDescription(patch.getDescription());
// apply only explicit, validated fields
repository.save(existing);
return existing;
}
}