CVE-2024-39561

Junos OS: SRX4600, SRX5000 Series: TCP packets with SYN/FIN or SYN/RST are transferred after enabling no-syn-check with Express Path

MEDIUM

5.8

CVSS Score

Published: July 10, 2024 at 10:46 PM UTC

Updated: June 17, 2026 at 07:42 AM UTC

6 products affected across 2 vendorsJunosSRX5800SRX5600

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Severity

MEDIUM5.8

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the flow daemon (flowd) of Juniper Networks Junos OS on SRX4600 and SRX5000 Series allows an attacker to send TCP packets with SYN/FIN or SYN/RST flags, bypassing the expected blocking of these packets. A TCP packet with SYN/FIN or SYN/RST should be dropped in flowd. However, when no-syn-check and Express Path are enabled, these TCP packets are unexpectedly transferred to the downstream network. This issue affects Junos OS on SRX4600 and SRX5000 Series: * All versions before 21.2R3-S8, * from 21.4 before 21.4R3-S7, * from 22.1 before 22.1R3-S6, * from 22.2 before 22.2R3-S4, * from 22.3 before 22.3R3-S3, * from 22.4 before 22.4R3-S2, * from 23.2 before 23.2R2, * from 23.4 before 23.4R1-S1, 23.4R2.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

v < 21.2v < 21.2R3-S821.4 ≤ v < 21.4r3-s722.1 ≤ v < 22.1R3-S622.2 ≤ v < 22.2R3-S422.3 ≤ v < 22.3R3-S322.4 ≤ v < 22.4r3-s223.2 ≤ v < 23.2R223.4 ≤ v < 23.4R1-S1, 23.4R221.2 21.2 r1 21.2 r1-s1 21.2 r1-s2 21.2 r2 21.2 r2-s1 21.2 r2-s2 21.2 r3 21.2 r3-s1 21.2 r3-s2 21.2 r3-s3 21.2 r3-s4 21.2 r3-s5 21.2 r3-s6 21.2 r3-s7 21.4 21.4 r1 21.4 r1-s1 21.4 r1-s2 21.4 r2 21.4 r2-s1 21.4 r2-s2 21.4 r3 21.4 r3-s1 21.4 r3-s2 21.4 r3-s3 21.4 r3-s4 21.4 r3-s5 21.4 r3-s6 22.1 22.1 r1 22.1 r1-s1 22.1 r1-s2 22.1 r2 22.1 r2-s1 22.1 r2-s2 22.1 r3 22.1 r3-s1 22.1 r3-s2 22.1 r3-s3 22.1 r3-s4 22.1 r3-s5 22.2 22.2 r1 22.2 r1-s1 22.2 r1-s2 22.2 r2 22.2 r2-s1 22.2 r2-s2 22.2 r3 22.2 r3-s1 22.2 r3-s2 22.2 r3-s3 22.3 22.3 r1 22.3 r1-s1 22.3 r1-s2 22.3 r2 22.3 r2-s1 22.3 r2-s2 22.3 r3 22.3 r3-s1 22.3 r3-s2 22.4 22.4 r1 22.4 r1-s1 22.4 r1-s2 22.4 r2 22.4 r2-s1 22.4 r2-s2 22.4 r3 22.4 r3-s1 23.2 23.2 r1 23.2 r1-s1 23.2 r1-s2 23.4 23.4 r1

Affected range stops below 21.2, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.2R3-S8, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.4R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.1R3-S6, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.3R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.4R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 23.2R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 23.4R1-S1, 23.4R2, so it looks safe — our inference, not a vendor statement

juniper-srx4600 (environment) · juniper-srx5000 (environment) · juniper-srx5400 (environment) · juniper-srx5600 (environment) · juniper-srx5800 (environment)

Srx4600 · Juniperdevice

80%

All versions

Srx5000 · Juniperdevice

80%

All versions

Srx5400 · Juniperdevice

80%

All versions

SRX5600 · Juniperdevice

80%

All versions