SB2026070856 - Improper Check for Unusual or Exceptional Conditions in Junos OS

Security Bulletin ID SB2026070856

CSH Severity

Medium

Patch available

YES

Number of vulnerabilities 1

Exploitation vector Adjecent network

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-2026-57020)

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

CVSSv4: CVSS:4.0/AV:A/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 non-authenticated attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper check for unusual or exceptional conditions error in the packet forwarding engine (pfe). A remote non-authenticated attacker can cause a Denial-of-Service (DoS).

On all QFX10000 platforms in an EVPN-VxLAN scenario, if an attacker sends IPv6 multicast traffic and these packets reach the non-IRB interface of a spine switch, it floods the packet to other spines and all Ethernet Segment Identifier (ESI) leaf switches.

Remediation

Install update from vendor's website.

References

https://supportportal.juniper.net/s/article/2026-07-Security-Bulletin-Junos-OS-QFX10000-Series-IPv6-multicast-traffic-received-on-non-IRB-interfaces-causes-a-multicast-flood-CVE-2026-57020