CVE-2024-39561 Security feature bypass in Junos OS

Medium 6.9 Published 10 Jul 2024 Updated 2 Aug 2024

Attackers can bypass TCP packet filtering on Juniper SRX devices by sending SYN/FIN or SYN/RST packets when specific non-default features are enabled.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2024-39561?

CVE-2024-39561 is a medium-severity vulnerability in Juniper Junos, published on 10 Jul 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-754

Which versions are affected by CVE-2024-39561?

It affects 1 product.

Products include Juniper Junos.

How do I fix CVE-2024-39561?

No fix has been published for CVE-2024-39561 yet. Limit exposure of the affected software until one is available.

Is CVE-2024-39561 being exploited?

There is no known exploitation of CVE-2024-39561 in the wild and no public exploit code.

All Juniper Junos vulnerabilities

Sources

Also known as GHSA-xvm6-65jm-mc4g.