Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Juniper Networks | Junos OS Evolved | < 23.4R2-S7-EVO, 24.2 – < 24.2R2-S5-EVO, 24.4 – < 24.4R2-S3-EVO, 25.2 – < 25.2R2-EVO | 23.4R2-S7-EVO |
Advisories 2
- NCSC-2026-0224 Kwetsbaarheden verholpen in Juniper Networks Junos OS en Junos OS Evolved NCSC-NL (Netherlands) · Jul 13, 2026
- WID-SEC-2026-2257 Juniper JUNOS und JUNOS Evolved: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 9, 2026
References
- https://supportportal.juniper.net/JSA110089 vendor-advisory