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High severity7.5NVD Advisory· Published Jan 15, 2026· Updated Jun 17, 2026

CVE-2026-21918

CVE-2026-21918

Description

A Double Free vulnerability in the flow processing daemon (flowd) of Juniper Networks Junos OS on SRX and MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On all SRX and MX Series platforms, when during TCP session establishment a specific sequence of packets is encountered a double free happens. This causes flowd to crash and the respective FPC to restart.

This issue affects Junos OS on SRX and MX Series:

  • all versions before 22.4R3-S7,
  • 23.2 versions before 23.2R2-S3,
  • 23.4 versions before 23.4R2-S4,
  • 24.2 versions before 24.2R2.

Affected products

36
  • Juniper Networks/Junos36 versions
    cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*+ 35 more
    • cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*range: <22.4
    • cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s5:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s6:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:*
    • (no CPE)range: <22.4R3-S7, <23.2R2-S3, <23.4R2-S4, <24.2R2
    • (no CPE)range: 0

Patches

Vulnerability mechanics

References

2

News mentions

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