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CVE-2021-31365

Junos OS: EX2300, EX3400 and EX4300 Series: An Aggregated Ethernet (AE) interface will go down due to a stream of specific layer 2 frames

Medium6.5EPSS 0.40%
Published
Updated
Reserved
Assigned by
juniper

Description

An Uncontrolled Resource Consumption vulnerability in Juniper Networks Junos OS on EX2300, EX3400 and EX4300 Series platforms allows an adjacent attacker sending a stream of layer 2 frames will trigger an Aggregated Ethernet (AE) interface to go down and thereby causing a Denial of Service (DoS). By continuously sending a stream of specific layer 2 frames an attacker will sustain the Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS EX4300 Series All versions prior to 15.1R7-S7; 16.1 versions prior to 16.1R7-S8; 17.1 versions prior to 17.1R2-S12; 17.2 versions prior to 17.2R3-S4; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S10, 17.4R3-S2; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R2-S7, 18.2R3-S3; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2; 18.4 versions prior to 18.4R1-S7, 18.4R2-S4, 18.4R3-S1; 19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S2, 19.3R3; 19.4 versions prior to 19.4R1-S2, 19.4R2. Juniper Networks Junos OS EX3400 and EX4300-MP Series All versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S9, 18.4R3-S7; 19.1 versions prior to 19.1R2-S3, 19.1R3-S4; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R3-S1; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3; 20.3 versions prior to 20.3R2. Juniper Networks Junos OS EX2300 Series All versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S9, 18.4R3-S9; 19.1 versions prior to 19.1R2-S3, 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S7, 19.3R3-S3; 19.4 versions prior to 19.4R3-S5; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R2.

Scores

CVSS scores of CVE-2021-31365, by who scored it
Scored byCVSSScoreVector
juniperCNA (assigner)3.1Medium6.5CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Modified3.1Medium6.5CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.40% · top 66% of all CVEs (6 Nov 2026)
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.

Weakness

Affected products

  • Juniper Networks · Junos OS

    • affected unspecified – < 15.1R7-S7
    • affected 16.1 – < 16.1R7-S8
    • affected 17.1 – < 17.1R2-S12
    • affected 17.2 – < 17.2R3-S4
    • affected 17.3 – < 17.3R3-S8
    • affected 17.4 – < 17.4R2-S10, 17.4R3-S2
    • affected 18.1 – < 18.1R3-S10
    • affected 18.2 – < 18.2R2-S7, 18.2R3-S3
    • affected 18.3 – < 18.3R2-S4, 18.3R3-S2
    • affected 18.4 – < 18.4R1-S7, 18.4R2-S4, 18.4R3-S1
    • affected 19.1 – < 19.1R1-S5, 19.1R2-S1, 19.1R3
    • affected 19.2 – < 19.2R1-S5, 19.2R2
    • affected 19.3 – < 19.3R2-S2, 19.3R3
    • affected 19.4 – < 19.4R1-S2, 19.4R2

  • Juniper Networks · Junos OS

    • affected unspecified – < 18.1R3-S12
    • affected 18.2 – < 18.2R3-S7
    • affected 18.3 – < 18.3R3-S4
    • affected 18.4 – < 18.4R2-S9, 18.4R3-S7
    • affected 19.1 – < 19.1R2-S3, 19.1R3-S4
    • affected 19.2 – < 19.2R3-S1
    • affected 19.3 – < 19.3R3-S1
    • affected 19.4 – < 19.4R3-S1
    • affected 20.1 – < 20.1R3
    • affected 20.2 – < 20.2R3
    • affected 20.3 – < 20.3R2

  • Juniper Networks · Junos OS

    • affected unspecified – < 18.3R3-S5
    • affected 18.4 – < 18.4R2-S9, 18.4R3-S9
    • affected 19.1 – < 19.1R2-S3, 19.1R3-S6
    • affected 19.2 – < 19.2R1-S7, 19.2R3-S3
    • affected 19.3 – < 19.3R2-S7, 19.3R3-S3
    • affected 19.4 – < 19.4R3-S5
    • affected 20.1 – < 20.1R2-S2, 20.1R3-S1
    • affected 20.2 – < 20.2R3-S2
    • affected 20.3 – < 20.3R3-S1
    • affected 20.4 – < 20.4R2-S1, 20.4R3
    • affected 21.1 – < 21.1R2

What to do

Solution: The following software releases have been updated to resolve this specific issue in Junos OS - For EX4300 Series: 15.1R7-S7, 16.1R7-S8, 17.1R2-S12, 17.2R3-S4, 17.3R3-S8, 17.4R2-S10, 17.4R3-S2, 18.1R3-S10, 18.2R2-S7, 18.2R3-S3, 18.3R2-S4, 18.3R3-S2, 18.4R1-S7, 18.4R2-S4, 18.4R3-S1, 19.1R1-S5, 19.1R2-S1, 19.1R3, 19.2R2, 19.3R2-S2, 19.3R3, 19.4R1-S2, 19.4R2, 20.1R1, and all subsequent releases. - For EX3400 and EX4300-MP Series: 18.1R3-S12, 18.2R3-S7, 18.3R3-S4, 18.4R2-S9, 18.4R3-S7, 19.1R2-S3, 19.1R3-S4, 19.2R3-S1, 19.3R3-S1, 19.4R3-S1, 20.1R3, 20.2R3, 20.3R2, 20.4R1, and all subsequent releases. -For EX2300 Series: 18.3R3-S5, 18.4R2-S9, 18.4R3-S9, 19.1R2-S3, 19.1R3-S6, 19.2R1-S7, 19.2R3-S3, 19.3R2-S7, 19.3R3-S3, 19.4R3-S5, 20.1R2-S2, 20.1R3-S1, 20.2R3-S2, 20.3R3-S1, 20.4R2-S1, 20.4R3, 21.1R2, 21.2R1, and all subsequent releases.

Workaround: Disabling LLDP configuration will prevent this issue.

Exploitation: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .