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

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.

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: 21.2R3-S8, 21.4R3-S7, 22.1R3-S6, 22.2R3-S4, 22.3R3-S3, 22.4R3-S2, 23.2R2, 23.4R1-S1, 23.4R2, 24.2R1, and all subsequent releases.

Workaround:

  • This issue can be mitigated by disabling Express Path: [set security forwarding-options services-offload disable]

Category

6.9
CVSS
Severity: Medium
CVSS 4.0 •
CVSS 3.1 •
EPSS 0.15%
Vendor Advisory juniper.net
Affected: Juniper Networks Junos OS
Published at:
Updated at:

References

Link Tags
https://supportportal.juniper.net/JSA83021 vendor advisory

Frequently Asked Questions

What is the severity of CVE-2024-39561?
CVE-2024-39561 has been scored as a medium severity vulnerability.
How to fix CVE-2024-39561?
To fix CVE-2024-39561: The following software releases have been updated to resolve this specific issue: 21.2R3-S8, 21.4R3-S7, 22.1R3-S6, 22.2R3-S4, 22.3R3-S3, 22.4R3-S2, 23.2R2, 23.4R1-S1, 23.4R2, 24.2R1, and all subsequent releases.
Is CVE-2024-39561 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2024-39561 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2024-39561?
CVE-2024-39561 affects Juniper Networks Junos OS.
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