CVE-2026-50735 in pglogical
Summary
by MITRE • 07/28/2026
pglogical's apply worker does not sufficiently validate the length of certain fields in incoming replication protocol messages before copying them, resulting in an out-of-bounds read. A party acting as the publisher for a subscription, for example a non-PostgreSQL endpoint that speaks the pglogical replication protocol, can return crafted messages that cause the subscriber's apply worker to read beyond the bounds of an allocated buffer, disclosing adjacent process memory or crashing the worker. To exploit the issue an attacker must be able to direct a subscription at an endpoint they control. In default installations this requires privileges normally reserved for a superuser, so the issue is most relevant to managed deployments where the ability to create subscriptions has been delegated to non-superuser roles.
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Analysis
by VulDB Data Team • 07/28/2026
The vulnerability in pglogical's apply worker represents a critical out-of-bounds read condition that arises from insufficient input validation during replication protocol message processing. This flaw exists within the replication subsystem of PostgreSQL logical replication extensions, specifically affecting how the apply worker handles incoming messages from publisher endpoints. The issue stems from the absence of proper bounds checking on field lengths before memory copying operations occur, creating a scenario where maliciously crafted replication messages can trigger unauthorized memory access patterns.
The technical implementation of this vulnerability manifests when pglogical processes replication protocol messages containing oversized fields that exceed expected buffer boundaries. During normal operation, the apply worker allocates fixed-size buffers to accommodate expected message formats, but fails to validate the actual length of incoming field data before copying it into these allocated spaces. This validation gap allows an attacker to craft messages with deliberately extended field values that cause the copy operation to read beyond allocated memory boundaries, potentially accessing adjacent memory regions containing sensitive information or causing process crashes.
From an operational perspective, this vulnerability creates significant security implications for PostgreSQL deployments using logical replication with pglogical. The attack vector requires that an attacker control a publisher endpoint that subscribers connect to, which typically necessitates elevated privileges due to the default configuration requiring superuser permissions for subscription creation. However, in managed environments where subscription creation capabilities have been delegated to non-superuser roles, this vulnerability becomes substantially more exploitable as attackers can potentially establish malicious endpoints without requiring full administrative access. The impact includes potential information disclosure through memory exposure and service disruption via worker crashes that can affect database availability.
The vulnerability aligns with CWE-129, which addresses improper validation of length of input buffers, and represents a classic example of buffer over-read conditions that can lead to information disclosure or denial of service. From an ATT&CK framework perspective, this maps to techniques involving privilege escalation and execution of malicious code through protocol manipulation, specifically targeting the database replication layer as a vector for information gathering. Organizations should prioritize mitigating this issue by implementing proper input validation mechanisms and ensuring that subscription creation privileges remain restricted to trusted administrative roles, while also considering network segmentation to limit exposure of replication endpoints to untrusted parties.
The remediation approach requires updating pglogical to implement comprehensive field length validation before memory copying operations, ensuring all incoming replication protocol fields are properly bounded before processing. Additionally, deployment configurations should restrict subscription creation capabilities to superuser accounts or implement additional authentication mechanisms for replication endpoint connections to minimize the attack surface available to unauthorized parties.