CVE-2026-33799 junos vulnerability
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.
Quick answer
juniper junos should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- 21.2
- 21.4
- 22.1
- 22.2
- 22.3
- 22.4
- 23.2
- 23.4
Fixed versions
- Apply the latest vendor-supported patched version.
How to fix it
Juniper Junos OS is affected by CVE-2026-33799, a denial-of-service risk. 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. The recommended remediation is to update to the Juniper fixed release for the installed branch, including 21.2R3-S8, 21.4R3-S7, 22.1R3-S6, 22.2R3-S4, 22.3R3-S3, 22.4R3-S2, 23.2R2, 23.4R2, or the matching EVO release. Until the update is complete, restrict SNMPv3 sources and monitor snmpd memory usage for exhaustion, review logs, and reduce exposure of the affected service or workflow.
- Inventory every deployment, package, appliance, container, service, and managed environment that uses Juniper Junos OS.
- Confirm the installed version and compare it with listed affected versions include 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, 23.2, 23.4 and the source advisory for CVE-2026-33799.
- Apply the vendor-supported fix: update to the Juniper fixed release for the installed branch, including 21.2R3-S8, 21.4R3-S7, 22.1R3-S6, 22.2R3-S4, 22.3R3-S3, 22.4R3-S2, 23.2R2, 23.4R2, or the matching EVO release.
- If the update cannot be applied immediately, restrict SNMPv3 sources and monitor snmpd memory usage for exhaustion; disable unnecessary public access, endpoints, plugins, integrations, or management interfaces until patched.
- Review application, device, reverse-proxy, WAF, package manager, container, authentication, and audit logs for activity related to CVE-2026-33799.
- Rotate sessions, API tokens, service credentials, integration keys, and administrator passwords if logs or affected data indicate compromise or unauthorized access.
- Clear caches, restart affected services, rebuild affected containers or appliances when appropriate, and remove temporary files or stored payloads created during exploitation attempts.
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Verify the fix
- Confirm Juniper Junos OS now reports the Juniper fixed release for the installed branch, including 21.2R3-S8, 21.4R3-S7, 22.1R3-S6, 22.2R3-S4, 22.3R3-S3, 22.4R3-S2, 23.2R2, 23.4R2, or the matching EVO release or a later vendor-supported fixed release for the deployed branch.
- Verify the affected workflow no longer allows the behavior described in CVE-2026-33799, using a safe regression test or vendor-provided validation method.
- Review logs after remediation for continued exploit attempts, denial-of-service symptoms, suspicious redirects, unauthorized requests, file access, or configuration changes.
- Rerun a Fixnx scan and any product-specific scanner, package audit, device health check, or manual regression test relevant to the affected service.
- Document affected assets, fixed versions, mitigation decisions, validation evidence, and any cleanup or credential rotation performed.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-33799?
juniper junos versions listed as affected should be reviewed: 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, 23.2, 23.4.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.