CVE-2026-33778

/// Technical description

An Improper Validation of Syntactic Correctness of Input vulnerability in the IPsec library used by kmd and iked of Juniper Networks Junos OS on SRX Series and MX Series allows an unauthenticated, network-based attacker to cause a complete Denial-of-Service (DoS).

If an affected device receives a specifically malformed first ISAKMP packet from the initiator, the kmd/iked process will crash and restart, which momentarily prevents new security associations (SAs) for from being established. Repeated exploitation of this vulnerability causes a complete inability to establish new VPN connections.

This issue affects Junos OS on

SRX Series and MX Series:

* all versions before 22.4R3-S9,

* 23.2 version before 23.2R2-S6,

* 23.4 version before 23.4R2-S7,

* 24.2 versions before 24.2R2-S4,

* 24.4 versions before 24.4R2-S3,

* 25.2 versions before 25.2R1-S2, 25.2R2.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References