CVE-2026-50738 in pglogical
Summary
by MITRE • 07/28/2026
A use-after-free condition exists in pglogical's worker signaling code, where a worker structure can be dereferenced after the underlying slot has been freed or recycled during normal worker lifecycle events. The condition is reachable during normal replication operation, including by a low-privileged user able to influence worker start, stop, and restart timing through permitted pglogical operations. In the typical case the condition crashes replication workers, causing an availability impact. In the worst case a use-after-free in a PostgreSQL backend can be leveraged as a remote code execution primitive at the privilege of that backend.
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Analysis
by VulDB Data Team • 07/28/2026
The vulnerability described represents a critical use-after-free condition within pglogical's worker signaling mechanism that fundamentally compromises system stability and security. This flaw exists in the PostgreSQL logical replication extension pglogical where worker structures are managed during normal replication operations. The issue arises from improper memory management practices where worker structures can be accessed after their underlying slot resources have been deallocated or recycled, creating a scenario where freed memory is still being referenced. The vulnerability is particularly concerning because it can be triggered through legitimate pglogical operations that any low-privileged user with appropriate permissions can execute, making it an accessible attack vector.
The technical implementation of this flaw occurs within the worker lifecycle management code where slot structures are freed or recycled during normal operational events such as worker start, stop, and restart sequences. When a worker structure references a slot that has already been freed, subsequent dereference operations result in use-after-free conditions that can manifest as memory corruption. This type of vulnerability maps directly to CWE-416 which specifically addresses the use of freed memory conditions in software systems. The condition becomes particularly dangerous during concurrent operations where timing attacks or race conditions can exacerbate the memory management issues, allowing for unpredictable behavior patterns.
The operational impact of this vulnerability manifests in multiple ways depending on the specific circumstances of exploitation. Under normal conditions, the use-after-free typically results in crashes of replication worker processes which directly impacts system availability and can cause disruption to database replication services. However, when exploited in more sophisticated scenarios, particularly within the PostgreSQL backend context, this vulnerability can be leveraged for remote code execution capabilities at the privilege level of the PostgreSQL backend process. This escalation potential transforms what initially appears as an availability issue into a serious security concern that could allow attackers to execute arbitrary code on the database server with elevated privileges.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1059.002 which covers command and scripting interpreter usage, particularly when considering how remote code execution could be achieved through backend process manipulation. The attack surface is expanded by the fact that legitimate pglogical operations can trigger this condition, meaning that any user with permission to manage replication workers can potentially influence the vulnerability state. Mitigation strategies should focus on implementing proper memory management practices within the worker lifecycle code, including reference counting mechanisms and proper synchronization primitives to prevent race conditions during slot deallocation. Additionally, input validation and access controls should be enhanced to limit unauthorized manipulation of worker lifecycle events that could trigger this condition. The fix requires careful attention to ensure that all references to worker structures are properly validated before dereferencing, particularly in multi-threaded environments where concurrent access patterns can compound the memory management issues.