CVE-2026-59787 in Zabbix
Summary
by MITRE • 10/05/2026
The Perl SNMP trap receiver script shipped with Zabbix does not properly neutralize the ZBXTRAP record delimiter in trap content. This means someone able to send SNMP traps can inject a record targeting another host, resulting in a loss of integrity.
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Analysis
by VulDB Data Team • 10/05/2026
The vulnerability identified involves a critical input validation flaw within the Perl-based Simple Network Management Protocol (SNMP) trap receiver script distributed with Zabbix monitoring software. The core technical deficiency lies in the improper neutralization or sanitization of specific record delimiters, specifically those associated with the ZBXTRAP protocol extension. When an SNMP agent sends a trap message to the Zabbix server, it includes data formatted according to the ZBXTRAP specification which relies on distinct delimiters to separate individual records within the payload. The script fails to adequately escape or validate these delimiter characters before processing them for internal use. This oversight creates a scenario where the boundary between one record and another is not strictly enforced by the application logic, allowing an attacker who has the capability to send SNMP traps to manipulate this structure.
From a technical perspective, this flaw constitutes an injection vulnerability within the context of network management protocols. By injecting specially crafted trap messages containing maliciously placed delimiters or data structures that mimic valid record boundaries, an adversary can effectively split what should be treated as a single logical unit into multiple distinct records. This manipulation allows the attacker to insert additional entries into the Zabbix database under the guise of legitimate monitoring data. The injection does not necessarily require code execution on the server itself but rather targets the integrity of the data ingestion pipeline. The system interprets these injected segments as valid, independent trap events originating from different sources or representing different metrics than intended by the original sender.
The operational impact of this vulnerability is primarily centered around a loss of data integrity and potential for false positive alerts within the monitoring infrastructure. An attacker can inject records targeting other hosts monitored by the same Zabbix instance. This means that an alert triggered by one compromised device could be falsely attributed to another, completely unrelated host in the network topology. Such misattribution can lead to significant operational confusion, causing system administrators to investigate non-existent issues on healthy systems while potentially overlooking actual problems on the targeted or original hosts. Furthermore, if downstream processes rely on this data for automated remediation actions based on specific trigger conditions, these actions could be executed against incorrect targets, leading to service disruptions or configuration changes applied to unintended assets.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-94, which describes Improper Control of Generation of Code ('Code Injection'), although in this context it is more accurately characterized as an injection into a structured data format rather than executable code. It also relates to CWE-20, Improper Input Validation, specifically regarding the failure to neutralize special elements that could be interpreted differently by the parser. In terms of the MITRE ATT&CK framework, this behavior maps to techniques involving Data Injection or Impair Defenses through false data generation, allowing an adversary to obscure their true activities and create noise within security monitoring tools. The exploitation requires network access to send SNMP traps but does not require authentication if the Zabbix server is configured to accept traps from untrusted sources without strict source IP verification or community string validation.
Mitigation strategies should focus on both immediate remediation and long-term architectural improvements. Administrators should immediately apply any available patches provided by Zabbix that address this specific input sanitization issue in the Perl trap receiver script. If patching is not immediately feasible, network-level controls such as Access Control Lists (ACLs) can be implemented to restrict SNMP traffic to only known and trusted management stations. Additionally, configuring the SNMP daemon on source devices to use secure community strings or transitioning to SNMPv3 with authentication and encryption capabilities will significantly reduce the risk of unauthorized trap injection. It is also advisable to review Zabbix trigger configurations for any automated actions that rely solely on incoming trap data without cross-referencing other telemetry sources, thereby limiting the blast radius if an injection occurs. Regular auditing of log integrity and monitoring for anomalous patterns in SNMP traffic can help detect exploitation attempts early.