Junos OS (SRX firewalls)
CVE-2026-33781: EX Series, QFX Series: In a VXLAN scenario when specific control protocol packets are received, memory leaks and eventually no traffic is passed
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX and QFX Series devices allow an unauthenticated, adjacent attacker to cause a complete Denial of Service (DoS).
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Junos OS (EX Series, QFX Series) 24.4 | 24.4R2 or later |
| Junos OS (EX Series, QFX Series) 25.2 | 25.2R1-S1, 25.2R2 or later |
| Junos OS (EX Series, QFX Series) 0 | Not affected |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX and QFX Series devices allow an unauthenticated, adjacent attacker to cause a complete Denial of Service (DoS).
On EX4k, and QFX5k platforms configured as service-provider edge devices, if L2PT is enabled on the UNI and VSTP is enabled on NNI in VXLAN scenarios, receiving VSTP BPDUs on UNI leads to packet buffer allocation failures, resulting in the device to not pass traffic anymore until it is manually recovered with a restart.This issue affects Junos OS:
- 24.4 releases before 24.4R2,
- 25.2 releases before 25.2R1-S1, 25.2R2.
This issue does not affect Junos OS releases before 24.4R1.
Workarounds
To prevent VSTP BPDUs from being processed on UNI interfaces configure:
[ protocols layer2-control bpdu-block interface all drop ]
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.