CVE-2026-48106 in Arc
Summary
by MITRE • 08/22/2026
Arc is an open, SQL-native time-series database for telemetry. Prior to version 26.06.1, Arc Enterprise's cluster replication receiver at `internal/cluster/replication/receiver.go` validates only the wire-format envelope (length, opcode) of inbound messages. The `MsgReplicateSync` payload itself is accepted without any application-layer authentication — no HMAC, no signature, no per-message nonce. The replication stream is protected at the transport layer by TLS / mTLS, but there is no protection against application-layer message tampering or replay once a peer is on the cluster network. This is fixed in 2026.06.1. Some workarounds are available. Restrict cluster network access to known-trusted peers via strict firewall rules, audit replication logs for unexpected `MsgReplicateSync` traffic, and/or disable cluster mode until the fix is available.
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Analysis
by VulDB Data Team • 08/22/2026
The vulnerability identified in Arc Enterprise prior to version 26.06.1 represents a critical failure in application-layer security controls within its SQL-native time-series database replication mechanism. While the system correctly implements transport layer encryption using TLS or mutual TLS, this protection only secures data in transit against eavesdropping and general network-level interception. It does not guarantee the integrity or authenticity of specific messages once they have been decrypted by a peer node that has successfully authenticated to the cluster network. The core flaw resides in the replication receiver logic located at internal/cluster/replication/receiver.go, which processes inbound synchronization requests with insufficient validation. Specifically, when handling MsgReplicateSync payloads, the system validates only basic wire-format attributes such as message length and opcode but completely omits any form of application-layer authentication. This absence includes missing HMAC verification, digital signatures, or per-message nonce checks that are standard practices for ensuring message origin integrity in distributed systems.
This architectural oversight creates a significant risk profile where an attacker who has gained access to the cluster network can manipulate replication streams without detection. Because there is no mechanism to verify that a MsgReplicateSync originates from a legitimate source node with valid credentials, malicious actors could inject forged synchronization commands or replay old messages to alter database state. This lack of message-level integrity control effectively undermines the security boundary established by TLS, as it allows for potential data corruption, unauthorized configuration changes, or denial-of-service conditions through malformed replication traffic. The vulnerability aligns closely with CWE-345 Insufficient Verification of Data Authenticity and falls under MITRE ATT&CK technique T1078 Valid Accounts if an attacker compromises a peer node to send these messages, or potentially T1190 Exploit Public-Facing Application if the network segmentation is weak enough to allow external access.
The operational impact of this flaw extends beyond simple data integrity concerns. In a clustered environment relying on Arc for telemetry storage and analysis, tampered replication can lead to inconsistent database states across nodes, causing query failures or incorrect analytics results that may go unnoticed until significant damage has occurred. Furthermore, the ability to replay messages could allow an attacker to revert recent changes or force redundant processing that degrades system performance. Since the vulnerability persists in all versions prior to 26.06.1, organizations running older builds are exposed to these risks as long as cluster mode is enabled and network access controls are not strictly enforced.
To mitigate this risk immediately upon discovery, administrators should implement strict firewall rules that restrict cluster communication exclusively to known-trusted peer IP addresses, thereby limiting the attack surface for any potential intruder who might attempt to inject malicious replication traffic. Additionally, auditing replication logs for unexpected MsgReplicateSync activity can help detect anomalous behavior indicative of exploitation attempts. Until upgrading to version 26.06.1 is feasible, disabling cluster mode entirely removes the vector for this specific vulnerability by halting inter-node synchronization processes that rely on the flawed receiver logic. The official fix in version 26.06.1 addresses these deficiencies by introducing proper application-layer authentication mechanisms such as HMAC and nonce validation to ensure that every replication message is both authentic and fresh, thereby closing the gap between transport security and data integrity guarantees.