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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

Quick assessment

Affected

Juniper Networks Junos OS

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Juniper Networks Junos OS是美国瞻博网络（Juniper Networks）公司的一套专用于该公司的硬件设备的网络操作系统。该操作系统提供了安全编程接口和Junos SDK。 Juniper Networks Junos OS 存在资源管理错误漏洞，该漏洞源于程序中的一个不受控制的资源消耗漏洞允许相邻攻击者发送第2层帧流将触发聚合以太网 (AE) 接口关闭，从而导致拒绝服务。

CVSS 6.5 · Medium EPSS 0.40% · P33 Updated Feb 25, 2026

Possible ATT&CK Techniques 2 AI

T1030 · Data Transfer Size Limits T1499 · Endpoint Denial of Service

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I. Basic Information for CVE-2021-31365

Vulnerability Information

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Vulnerability Title

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

Source: CVE Program / CVE List V5

Vulnerability 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.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Source: CVE Program / CVE List V5

Vulnerability Type

未加控制的资源消耗(资源穷尽)

Source: CVE Program / CVE List V5

Vulnerability Title

Juniper Networks Junos OS 资源管理错误漏洞

Source: CNNVD (China National Vulnerability Database)

Vulnerability Description

Source: CNNVD (China National Vulnerability Database)

CVSS Information

N/A

Source: CNNVD (China National Vulnerability Database)

Vulnerability Type

N/A

Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor	Product	Affected Versions	CPE
Juniper Networks	Junos OS	unspecified ~ 15.1R7-S7	-
Juniper Networks	Junos OS	unspecified ~ 18.1R3-S12	-
Juniper Networks	Junos OS	unspecified ~ 18.3R3-S5	-

II. Public POCs for CVE-2021-31365

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2021-31365

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Vendor Advisories for CVE-2021-31365 (1)

https://kb.juniper.net/JSA11227 x_refsource_CONFIRM

https://www.cve.org/CVERecord?id=CVE-2021-31365

Same Patch Batch · Juniper Networks · 2021-10-19 · 42 CVEs total

CVE-2021-31349	9.8 CRITICAL	Session Smart Router: Authentication Bypass Vulnerability
CVE-2021-31385	8.8 HIGH	Junos OS: J-Web: A path traversal vulnerability allows an authenticated attacker to elevat
CVE-2021-31372	8.8 HIGH	Junos OS: J-Web allows a locally authenticated attacker to escalate their privileges to ro
CVE-2021-31355	8.0 HIGH	Junos OS: Stored Cross-Site Scripting (XSS) vulnerability in captive portal
CVE-2021-31373	8.0 HIGH	Junos OS: SRX Series: Persistent XSS vulnerability in J-Web
CVE-2021-31356	7.8 HIGH	Junos OS Evolved: Multiple shell-injection vulnerabilities in EVO UI wrapper scripts
CVE-2021-31357	7.8 HIGH	Junos OS Evolved: shell-injection vulnerabilities in evo_tcpdump UI wrapper script
CVE-2021-31358	7.8 HIGH	Junos OS Evolved: shell-injection vulnerabilities in evo_sftp UI wrapper script
CVE-2021-31359	7.8 HIGH	Junos OS and Junos OS Evolved: Local Privilege Escalation vulnerability
CVE-2021-31350	7.5 HIGH	Junos OS and Junos OS Evolved: Privilege escalation vulnerability in Juniper Extension Too
CVE-2021-31351	7.5 HIGH	Junos OS: MX Series: Receipt of specific packet on MS-MPC/MS-MIC causes line card reset
CVE-2021-31379	7.5 HIGH	Junos OS: MX Series: MPC 7/8/9/10/11 cards with MAP-E: PFE halts when an attacker sends ma
CVE-2021-31353	7.5 HIGH	Junos OS and Junos OS Evolved: RPD core upon receipt of specific BGP update
CVE-2021-31376	7.5 HIGH	Junos OS: ACX Series: Packet Forwarding Engine manager (FXPC) process crashes when process
CVE-2021-31374	7.5 HIGH	Junos OS and Junos OS Evolved: RPD crash while processing a specially crafted BGP UPDATE o
CVE-2021-31383	7.5 HIGH	Junos OS and Junos OS Evolved: In Point to MultiPoint (P2MP) scenarios receipt of various
CVE-2021-0299	7.5 HIGH	Junos OS: Kernel crash (vmcore) upon receipt of a malformed IPv6 packet
CVE-2021-31368	7.5 HIGH	Junos OS: EX2300 Series, EX3400 Series, and ACX710 might become unresponsive if the out-of
CVE-2021-0296	7.4 HIGH	CTPView: HSTS not being enforced on CTPView server.
CVE-2021-31384	7.2 HIGH	Junos OS: SRX Series: Under a specific device configuration an attacker can access the dev

Showing top 20 of 42 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Junos OS

Same vendor: Juniper Networks

Same weakness: CWE-400

V. Comments for CVE-2021-31365

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Goal Reached Thanks to every supporter — we hit 100%!

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

Quick assessment

Possible ATT&CK Techniques 2 AI

I. Basic Information for CVE-2021-31365

Vulnerability Information

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Affected Products

II. Public POCs for CVE-2021-31365

III. Intelligence Information for CVE-2021-31365

Vendor Advisories for CVE-2021-31365 (1)

Same Patch Batch · Juniper Networks · 2021-10-19 · 42 CVEs total

IV. Related Vulnerabilities

V. Comments for CVE-2021-31365

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