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The vulnerability in Hibernate Reactive stems from inadequate handling of database connection lifecycle during premature HTTP connection closures. When an HTTP endpoint exposes database operations, remote clients can abort connections before responses complete. In reactive programming, database interactions are asynchronous, with connections borrowed from a pool. Upon early client disconnection, the reactive chain cancellation may not propagate properly to the connection pool manager. This results in acquired database connections not being released back to the pool, causing leaks. Over time, repeated malicious requests exhaust all available connections in the pool. Once exhausted, new database operations fail, leading to Denial of Service. The issue is specific to reactive frameworks where non-blocking I/O and cancellation signals are mismanaged. Attackers exploit this by sending requests and abruptly terminating them, depleting pool resources without triggering cleanup. The flaw affects environments with high concurrency and limited pool configuration. Patched versions ensure connection release is tied to cancellation events, preventing leaks.
Platform: Hibernate Reactive
Version: < 4.2.1
Vulnerability: Connection Pool Exhaustion
Severity: Moderate
Date: Jan 26 2026
Prediction: Patched Jan 27 2026
What Undercode Say:
curl –max-time 0.5 http://endpoint
netcat abort simulation
mvn dependency:tree grep
vulnerable endpoint code
@GET @Path public Uni
how Exploit:
Send HTTP requests
Abort connections prematurely
Repeat to exhaust pool
Protection from this CVE
Upgrade to 4.2.1
Monitor connection pools
Implement rate limiting
Impact:
Denial of Service
Resource exhaustion
Application downtime
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
