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CVE-2026-57023

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 23.4R2-S7, 24.2R2-S4, 24.4R2-S3, 25.2R2
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • Juniper Networks Junos OS

    From 23.4 · fixed in 23.4R2-S7; From 24.2 · fixed in 24.2R2-S4; From 24.4 · fixed in 24.4R2-S3; From 25.2 · fixed in 25.2R2

References 1

supportportal.juniper.net