CVE-2026-41732: In Spring for Apache Pulsar, overly broad trusted-package matching in header mapper exposes JDK classes to deserialization

Synopsis

This is an unsafe deserialization vulnerability in Spring for Apache Pulsar's JsonPulsarHeaderMapper component. The flaw is reachable over the network with no authentication required, though exploitation requires high attack complexity due to environmental preconditions. A successful attacker can read sensitive data, tamper with application state, and crash the affected service. Patched-image rebuilds at versions 1.1.18, 1.2.18, and 2.0.6 are available on HarborGuard for environments running affected versions.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the Pulsar messaging endpoint over the network; no local or physical access is needed, but the service must be exposed to the attacker's network path.

• AuthenticationNot required

  No credentials or account are needed; an unauthenticated attacker can send crafted message headers directly to the endpoint.

• Victim interactionNot required

  Exploitation is fully attacker-driven and requires no action from a user or operator of the affected service.

• Attack complexityDetail

  Attack complexity is rated HIGH, meaning the attacker must engineer specific environmental conditions, such as controlling the content of Pulsar message type headers and ensuring the target application processes them through the vulnerable mapper.

Blast Radius

• An attacker who achieves arbitrary deserialization can read application secrets, credentials, and in-memory session state accessible to the JVM process.
• Deserialization gadget chains allow the attacker to write or modify persisted data, including database rows or file-system state reachable by the application.
• Full remote code execution is achievable through known JDK deserialization gadget chains, giving the attacker control over the host process.
• The attacker can crash the affected Pulsar consumer or producer process, causing a service disruption for any workloads that depend on the message pipeline.