Juniper Junos OS/Junos OS Evolved prior 21.2R3-S8/21.2R3-S8-EVO SNMP Daemon out-of-bounds write

Summaryinfo

A vulnerability categorized as critical has been discovered in Juniper Junos OS and Junos OS Evolved. This affects an unknown function of the component SNMP Daemon. Executing a manipulation can lead to out-of-bounds write. This vulnerability appears as CVE-2026-33799. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in Juniper Junos OS and Junos OS Evolved. This vulnerability affects an unknown functionality of the component SNMP Daemon. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect availability. CVE summarizes:

An Out-of-bounds Write vulnerability in the SNMP daemon (snmpd) of Juniper Networks Junos OS and Junos OS Evolved allows an authenticated network-based attacker sending specific valid SNMPv3 queries to trigger a memory leak. Over time, continuous receipt of these queries will result in snmpd process memory exhaustion, resulting in a process crash and restart, impacting the ability to monitor the system via SNMP. Memory usage can be monitored using the following command: user@device> show system processes extensive | match snmpd This issue affects: Junos OS: * all versions before 21.2R3-S8; * from 21.4 before 21.4R3-S7; * from 22.1 before 22.1R3-S6; * from 22.2 before 22.2R3-S4; * from 22.3 before 22.3R3-S3; * from 22.4 before 22.4R3-S2; * from 23.2 before 23.2R2; * from 23.4 before 23.4R2. Junos OS Evolved: * all versions before 21.2R3-S8-EVO; * from 21.4 before 21.4R3-S7-EVO; * all versions of 22.1-EVO, * from 22.2 before 22.2R3-S4-EVO; * from 22.3 before 22.3R3-S3-EVO; * all versions of 22.4-EVO, * from 23.2 before 23.2R2-EVO; * from 23.4 before 23.4R2-EVO.

The advisory is shared for download at supportportal.juniper.net. This vulnerability was named CVE-2026-33799 since 03/23/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/09/2026).

Upgrading to version 21.2R3-S8 or 21.2R3-S8-EVO eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Juniper

Name

• Junos OS
• Junos OS Evolved

License

• commercial

Website

• Vendor: https://www.juniper.net/

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