CVE-2026-57031
Junos OS: MX Series: For subscribers configured on static interfaces, input filters are not in effect
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters.
On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect.
This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304:
- 23.2 versions from 23.2R2-S1 before 23.2R2-S7,
- 23.4 versions from 23.4R2 before 23.4R2-S7,
- 24.2 versions before 24.2R2-S3,
- 24.4 versions before 24.4R2-S2,
- 25.2 versions before 25.2R2.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Junos OS: MX Series: For subscribers configured on static interfaces, input filters are not in effect
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters.
On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect.
This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304:
- 23.2 versions from 23.2R2-S1 before 23.2R2-S7,
- 23.4 versions from 23.4R2 before 23.4R2-S7,
- 24.2 versions before 24.2R2-S3,
- 24.4 versions before 24.4R2-S2,
- 25.2 versions before 25.2R2.
- Record
CVE-2026-57031- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/AU:Y/RE:M - CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N - Weakness
- CWE-754
- Updated
- 2026-11-02
EUVDEUVD-2026-42721
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters.
On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect.
This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304:
- 23.2 versions from 23.2R2-S1 before 23.2R2-S7,
- 23.4 versions from 23.4R2 before 23.4R2-S7,
- 24.2 versions before 24.2R2-S3,
- 24.4 versions before 24.4R2-S2,
- 25.2 versions before 25.2R2.
- Record
EUVD-2026-42721- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/AU:Y/RE:M - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-7v7x-35fg-5xc8
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding...
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters.
On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect.
This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304:
- 23.2 versions from 23.2R2-S1 before 23.2R2-S7,
- 23.4 versions from 23.4R2 before 23.4R2-S7,
- 24.2 versions before 24.2R2-S3,
- 24.4 versions before 24.4R2-S2,
- 25.2 versions before 25.2R2.
- Record
GHSA-7v7x-35fg-5xc8- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:X/V:X/RE:M/U:X - CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N - Weakness
- CWE-754
- Updated
- 2026-11-02
NVD
An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters.
On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect.
This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304:
- 23.2 versions from 23.2R2-S1 before 23.2R2-S7,
- 23.4 versions from 23.4R2 before 23.4R2-S7,
- 24.2 versions before 24.2R2-S3,
- 24.4 versions before 24.4R2-S2,
- 25.2 versions before 25.2R2.
- Record
CVE-2026-57031- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:X/V:X/RE:M/U:X - CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N - Weakness
- CWE-754
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-57031 is a medium vulnerability (CVSS 5.3) in Juniper Junos, published July 9, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 13th percentile. No source names a fixed version.