SB2026040942 - Remote denial of service in Junos OS IPsec

Security Bulletin ID SB2026040942

CSH Severity

Medium

Patch available

YES

Number of vulnerabilities 1

Exploitation vector Remote access

Highest impact Denial of service

Breakdown by Severity

Low
Medium
High
Critical

Description

This security bulletin contains information about 1 vulnerability.

1) Improper input validation (CVE-ID: CVE-2026-33778)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper validation of syntactic correctness of input in the IPsec library used by kmd and iked when processing a specifically malformed first ISAKMP packet. A remote attacker can send a specifically malformed first ISAKMP packet to cause a denial of service.

Successful exploitation crashes and restarts the kmd/iked process, which momentarily prevents new security associations from being established. Repeated exploitation can prevent new VPN connections from being established.

Remediation

Install update from vendor's website.

References

https://supportportal.juniper.net/s/article/2026-04-Security-Bulletin-Junos-OS-SRX-Series-MX-Series-When-a-specifically-malformed-first-ISAKMP-packet-is-received-kmd-iked-crashes-CVE-2026-33778