CVE-2026-48006: Netty's Lack of Lifecycle Cleanup Leads to Pooled ByteBuf Leak in RedisArrayAggregator
Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, the RedisArrayAggregator handler permanently leaks pooled direct-memory buffers when a Redis pipeline connection closes before a RESP array aggregate completes. The handler retains child messages in per-handler state (`depths` field) but defines no `channelInactive`, `handlerRemoved`, or `exceptionCaught` method to release them when the pipeline tears down. Because the leaked buffers are slices of `PooledByteBufAllocator` chunks, they prevent those chunks from being returned to the JVM-wide direct-memory pool. Repeated connection churn by any network peer monotonically drains this shared pool, eventually causing allocation failures on all Netty channels in the process. Versions 4.1.135.Final and 4.2.15.Final patch the issue.
Security readout for executives and security teams
Plain-English summary
A flaw in Netty can let repeated interrupted Redis protocol connections leak off-heap memory until the Java process can no longer allocate buffers. The business impact is availability: services using the affected Redis aggregation path may fail or degrade under network-driven churn.
Executive priority
Treat as a high-priority availability risk for internet-facing or shared Java services using Netty Redis handling. Prioritize patching exposed services first, then dependent internal services with high operational criticality.
Technical view
Before Netty 4.1.135.Final and 4.2.15.Final, RedisArrayAggregator retained pooled child ByteBuf messages but lacked cleanup on channel inactivity, handler removal, or exceptions. Incomplete RESP arrays could leave pooled direct-memory slices unreleased, draining the shared allocator pool and causing process-wide allocation failures.
Likely exposure
Exposure is most likely in Java services using affected Netty versions with RedisArrayAggregator or related Redis pipeline handling reachable by untrusted or unreliable peers. Netty deployments not using this handler path may have limited practical exposure.
Exploitation context
The source bundle marks KEV as false and provides no evidence of active exploitation. The CVSS vector indicates network access, low complexity, no privileges, and no user interaction, with high availability impact.
Researcher notes
The root issue is missing lifecycle release for retained pooled buffers in RedisArrayAggregator state. Evidence supports a denial-of-service memory leak, not confidentiality or integrity compromise. Supplied sources do not include exploit code or confirmed exploitation.
Mitigation direction
Upgrade Netty to 4.1.135.Final or 4.2.15.Final.
Apply listed Red Hat errata where Red Hat packages provide Netty.
Restrict Redis protocol endpoints from untrusted network peers where feasible.
Monitor direct-memory pressure and Netty allocation failures until patched.
Check vendor guidance if upgrade timing or product impact is unclear.
Validation and detection
Inventory applications and dependencies for affected Netty versions.
Confirm whether RedisArrayAggregator is used in reachable code paths.
Verify runtime dependency resolution, not only declared build files.
Review logs and metrics for direct-memory exhaustion symptoms.
Confirm fixed versions are deployed after remediation.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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Missing Release of Memory after Effective Lifetime
Missing Release of Memory after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Missing Release of Resource after Effective Lifetime
Missing Release of Resource after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.