SB2026012023 - Unchecked Return Value in Juniper Junos OS
Published: January 20, 2026
Security Bulletin ID
SB2026012023
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 security vulnerability.
1) Unchecked Return Value (CVE-ID: CVE-2026-21920)
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to unchecked return value error in the DNS module. A remote non-authenticated attacker can cause a Denial-of-Service (DoS).
If an SRX Series device configured for DNS processing, receives a specifically formatted DNS request flowd will crash and restart, which causes a service interruption until the process has recovered.
Remediation
Install update from vendor's website.