CVE-2021-31365

CVE-2021-31365 is a medium-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

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.

Frequently asked questions

What is CVE-2021-31365?
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.
How severe is CVE-2021-31365?
CVE-2021-31365 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-31365 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31365?
CVE-2021-31365 primarily affects Juniper Junos. In total, 334 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31365?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-31365 published?
CVE-2021-31365 was published on 2021-10-19 and last updated on 2026-06-17.

References

Affected products (334)

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