Junos OS (SRX firewalls)
CVE-2025-52951: IPv6 firewall filter fails to match payload-protocol
A Protection Mechanism Failure vulnerability in kernel filter processing of Juniper Networks Junos OS allows an attacker sending IPv6 traffic destined to the device to effectively bypass any firewall filtering configured on the interface.
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 0 | 21.2R3-S9 or later |
| Junos OS 21.4 | 21.4R3-S11 or later |
| Junos OS 22.2 | 22.2R3-S7 or later |
| Junos OS 22.4 | 22.4R3-S7 or later |
| Junos OS 23.2 | 23.2R2-S4 or later |
| Junos OS 23.4 | 23.4R2-S5 or later |
| Junos OS 24.2 | 24.2R2-S1 or later |
| Junos OS 24.4 | 24.4R1-S2, 24.4R2 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
A Protection Mechanism Failure vulnerability in kernel filter processing of Juniper Networks Junos OS allows an attacker sending IPv6 traffic destined to the device to effectively bypass any firewall filtering configured on the interface.
Due to an issue with Junos OS kernel filter processing, the 'payload-protocol' match is not being supported, causing any term containing it to accept all packets without taking any other action. In essence, these firewall filter terms were being processed as an 'accept' for all traffic on the interface destined for the control plane, even when used in combination with other match criteria.
This issue only affects firewall filters protecting the device's control plane. Transit firewall filtering is unaffected by this vulnerability.
This issue affects Junos OS:
- all versions before 21.2R3-S9,
- from 21.4 before 21.4R3-S11,
- from 22.2 before 22.2R3-S7,
- from 22.4 before 22.4R3-S7,
- from 23.2 before 23.2R2-S4,
- from 23.4 before 23.4R2-S5,
- from 24.2 before 24.2R2-S1,
- from 24.4 before 24.4R1-S2, 24.4R2.
This is a more complete fix for previously published CVE-2024-21607 (JSA75748).
Am I affected?
The following firewall filter configuration, using payload-protocol, will fail to match, allowing traffic to be accepted, rather than discarded:
[firewall family inet6 filter example-filter term reject-tcp from payload-protocol tcp] [firewall family inet6 filter example-filter term reject-tcp then discard] [firewall family inet6 filter example-filter term allow-rest then accept]
Workarounds
Utilize 'next-header' match instead of 'payload-protocol' in any firewall filter configurations.
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.