Juniper Junos OS Evolved Flow Collector improper synchronization

Summaryinfo

A vulnerability identified as critical has been detected in Juniper Junos OS Evolved. The impacted element is an unknown function of the component Flow Collector. The manipulation leads to improper synchronization. This vulnerability is documented as CVE-2026-57029. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Juniper Junos OS Evolved. It has been rated as critical. This issue affects some unknown functionality of the component Flow Collector. The manipulation with an unknown input leads to a improper synchronization vulnerability. Using CWE to declare the problem leads to CWE-662. The product utilizes multiple threads or processes to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes. Impacted is availability. The summary by CVE is:

A Missing Synchronization vulnerability in the flow collector handler of Juniper Networks Junos OS Evolved on QFX Series allows an adjacent, unauthenticated attacker to cause a Denial-of-Service (DoS). When the reachability of an sFlow collector changes, the corresponding next-hop entry is updated. If this update occurs simultaneously with the sFlow thread accessing the next-hop data (which is outside the attackers control), it causes the evo-pfemand process to crash, impacting all traffic forwarding until the automatic process restart has completed. This issue affects Junos OS Evolved on QFX Series: * all 23.2 versions,  * 23.4 versions before 23.4R2-S7-EVO, * 24.2 versions before 24.2R2-S5-EVO, * 24.4 versions before 24.4R2-S3-EVO, * 25.2 versions before 25.2R2-EVO.

It is possible to read the advisory at supportportal.juniper.net. The identification of this vulnerability is CVE-2026-57029 since 06/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/10/2026).

Upgrading to version 23.4R2-S7-EVO, 24.2R2-S5-EVO, 24.4R2-S3-EVO or 25.2R2-EVO eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Juniper

Name

• Junos OS Evolved

License

• commercial

Website

• Vendor: https://www.juniper.net/

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