When configuring stateless firewall filters in Juniper Networks EX4600 and QFX 5000 Series devices using Virtual Extensible LAN protocol (VXLAN), the discard action will fail to discard traffic under certain conditions. Given a firewall filter configuration similar to: family ethernet-switching { filter L2-VLAN { term ALLOW { from { user-vlan-id 100; } then { accept; } } term NON-MATCH { then { discard; } } when there is only one term containing a 'user-vlan-id' match condition, and no other terms in the firewall filter except discard, the discard action for non-matching traffic will only discard traffic with the same VLAN ID specified under 'user-vlan-id'. Other traffic (e.g. VLAN ID 200) will not be discarded. This unexpected behavior can lead to unintended traffic passing through the interface where the firewall filter is applied. This issue only affects systems using VXLANs. This issue affects Juniper Networks Junos OS on QFX5K Series: 18.1 versions prior to 18.1R3-S7, except 18.1R3; 18.2 versions prior to 18.2R2-S7, 18.2R3-S1; 18.3 versions prior to 18.3R1-S5, 18.3R2-S4, 18.3R3; 18.4 versions prior to 18.4R1-S7, 18.4R2-S1, 18.4R3; 19.1 versions prior to 19.1R1-S5, 19.1R2; 19.2 versions prior to 19.2R1-S5, 19.2R2.
Published 2020-10-16 21:15:14
Updated 2021-02-05 16:49:04
View at NVD,   CVE.org

Exploit prediction scoring system (EPSS) score for CVE-2020-1685

0.08%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 35 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-1685

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
5.0
MEDIUM AV:N/AC:L/Au:N/C:N/I:P/A:N
10.0
2.9
NIST
5.8
MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
3.9
1.4
Juniper Networks, Inc.

CWE ids for CVE-2020-1685

  • The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not.
    Assigned by:
    • nvd@nist.gov (Primary)
    • sirt@juniper.net (Secondary)

References for CVE-2020-1685

  • https://kb.juniper.net/JSA11082
    2020-10 Security Bulletin: Junos OS: EX4600, QFX5K Series: Stateless firewall filter matching 'user-vlan-id' will cause incomplete discard action (CVE-2020-1685) - Juniper Networks
    Vendor Advisory

Products affected by CVE-2020-1685

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