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CVE-2021-0243

MEDIUM
Published 2021-04-22T19:37:08.073257Z
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CVSS Score

V3.1
4.7
/10
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Base Score Metrics
Exploitability: N/A Impact: N/A

EPSS Score

v2025.03.14
0.001
probability
of exploitation in the wild

There is a 0.1% chance that this vulnerability will be exploited in the wild within the next 30 days.

Updated: 2025-06-25
Exploit Probability
Percentile: 0.241
Higher than 24.1% of all CVEs

Attack Vector Metrics

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED

Impact Metrics

Confidentiality
NONE
Integrity
NONE
Availability
LOW

Description

Improper Handling of Unexpected Data in the firewall policer of Juniper Networks Junos OS on EX4300 switches allows matching traffic to exceed set policer limits, possibly leading to a limited Denial of Service (DoS) condition. When the firewall policer discard action fails on a Layer 2 port, it will allow traffic to pass even though it exceeds set policer limits. Traffic will not get discarded, and will be forwarded even though a policer discard action is configured. When the issue occurs, traffic is not discarded as desired, which can be observed by comparing the Input bytes with the Output bytes using the following command: user@junos> monitor interface traffic Interface Link Input bytes (bps) Output bytes (bps) ge-0/0/0 Up 37425422 (82616) 37425354 (82616) <<<< egress ge-0/0/1 Up 37425898 (82616) 37425354 (82616) <<<< ingress The expected output, with input and output counters differing, is shown below: Interface Link Input bytes (bps) Output bytes (bps) ge-0/0/0 Up 342420570 (54600) 342422760 (54600) <<<< egress ge-0/0/1 Up 517672120 (84000) 342420570 (54600) <<<< ingress This issue only affects IPv4 policing. IPv6 traffic and firewall policing actions are not affected by this issue. This issue affects Juniper Networks Junos OS on the EX4300: All versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S6; 19.1 versions prior to 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2.

Available Exploits

No exploits available for this CVE.

Related News

No news articles found for this CVE.

Affected Products

Juniper Networks

Junos OS

Affected Versions:

unspecified 17.4 18.1 18.2 18.3 18.4 19.1 19.2 19.3 19.4 20.1 20.2

GitHub Security Advisories

Community-driven vulnerability intelligence from GitHub

⚠ Unreviewed MODERATE

GHSA-686h-45gr-mc75

Advisory Details

Improper Handling of Unexpected Data in the firewall policer of Juniper Networks Junos OS on EX4300 switches allows matching traffic to exceed set policer limits, possibly leading to a limited Denial of Service (DoS) condition. When the firewall policer discard action fails on a Layer 2 port, it will allow traffic to pass even though it exceeds set policer limits. Traffic will not get discarded, and will be forwarded even though a policer discard action is configured. When the issue occurs, traffic is not discarded as desired, which can be observed by comparing the Input bytes with the Output bytes using the following command: user@junos> monitor interface traffic Interface Link Input bytes (bps) Output bytes (bps) ge-0/0/0 Up 37425422 (82616) 37425354 (82616) <<<< egress ge-0/0/1 Up 37425898 (82616) 37425354 (82616) <<<< ingress The expected output, with input and output counters differing, is shown below: Interface Link Input bytes (bps) Output bytes (bps) ge-0/0/0 Up 342420570 (54600) 342422760 (54600) <<<< egress ge-0/0/1 Up 517672120 (84000) 342420570 (54600) <<<< ingress This issue only affects IPv4 policing. IPv6 traffic and firewall policing actions are not affected by this issue. This issue affects Juniper Networks Junos OS on the EX4300: All versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S6; 19.1 versions prior to 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2.

CVSS Scoring

CVSS Score

5.0

References

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2021-0243
WEB https://kb.juniper.net/JSA11136

Advisory provided by GitHub Security Advisory Database. Published: May 24, 2022, Modified: May 24, 2022

References

https://kb.juniper.net/JSA11136
Published: 2021-04-22T19:37:08.073257Z
Last Modified: 2024-09-17T00:51:52.928Z
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