CVE-2026-33778: SRX Series, MX Series: When a specifically malformed first ISAKMP packet is received kmd/iked crashes

Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.

Affected and fixed versions

Product / branch	Fixed in
Junos OS (SRX Series, MX Series) 0	22.4R3-S9 or later
Junos OS (SRX Series, MX Series) 23.2	23.2R2-S6 or later
Junos OS (SRX Series, MX Series) 23.4	23.4R2-S7 or later
Junos OS (SRX Series, MX Series) 24.2	24.2R2-S4 or later
Junos OS (SRX Series, MX Series) 24.4	24.4R2-S3 or later
Junos OS (SRX Series, MX Series) 25.2	25.2R1-S2, 25.2R2 or later

Always confirm against the vendor advisory, which lists every fixed hotfix.

What it is

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.

Am I affected?

An SRX or MX device is only exploitable when it is configured for IPsec VPN services.

Workarounds

There are no known workarounds for this issue.

Exploitation

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.