SB2026050823 - Remote denial of service in Junos OS ICMPv6 handling

Security Bulletin ID SB2026050823

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 Check for Unusual or Exceptional Conditions (CVE-ID: CVE-2026-33790)

CWE-ID: CWE-754 - Improper Check for Unusual or Exceptional Conditions

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 check for unusual or exceptional conditions in the flow daemon (flowd) when processing a specific malformed ICMPv6 packet during NAT64 translation. A remote attacker can send a specially crafted ICMPv6 packet to cause a denial of service.

This issue requires a NAT64 configuration to be present and cannot be triggered using IPv4 or other IPv6 traffic.

Remediation

Install update from vendor's website.

References

https://supportportal.juniper.net/s/article/2026-04-Security-Bulletin-Junos-OS-SRX-Series-In-a-NAT64-configuration-receipt-of-a-specific-malformed-ICMPv6-packet-will-cause-the-srxpfe-process-to-crash-and-restart-CVE-2026-33790