CVE-2026-57023 HIGH

CVE-2026-57023: Junos OS: MX with SPC3, SRX Series: A specifically malformed TCP packet causes a flowd crash

Vendor Juniper Networks
Product Junos OS
Weakness CWE-1284
Published July 9, 2026
Last update July 10, 2026

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

An Improper Validation of Specified Quantity in Input vulnerability in the TCP proxy plugin of Juniper Networks Junos OS on MX Series with SPC3, and SRX Series allows an unauthenticated, network-based attacker to cause a complete Denial of Service (DoS). When TCP proxy is engaged in a flow session, to support ALGs, Advanced Anti-Malware, ICAP or UTM, a TCP packet with specifically malformed TCP header will cause flow processing daemon (flowd) to crash and restart. This causes a complete service outage until the system has automatically recovered. This issue affects Junos OS on MX with SPC3, and SRX Series:  * 23.4 versions before 23.4R2-S7,  * 24.2 versions before 24.2R2-S4,  * 24.4 versions before 24.4R2-S3, * 25.2 versions before 25.2R2. This issue does not affect releases before 23.4R1.

Key dates

02Disclosure timeline

July 9, 2026 CVE published
July 10, 2026 Record updated

Related vulnerabilities

04Related CVE