CVE-2021-0243

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: [email protected]> 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.

References


Vendor Advisory

CvssV3 impact


Version

3.1

VectorString

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

AttackVector

ADJACENT_NETWORK

AttackComplexity

LOW

PrivilegesRequired

NONE

UserInteraction

NONE

Scope

CHANGED

ConfidentialityImpact

NONE

IntegrityImpact

NONE

AvailabilityImpact

LOW

BaseScore

4.7

BaseSeverity

MEDIUM

CvssV2 impact


AccessComplexity

LOW

ConfidentialityImpact

NONE

AvailabilityImpact

PARTIAL

IntegrityImpact

NONE

BaseScore

3.3

VectorString

AV:A/AC:L/Au:N/C:N/I:N/A:P

Version

2.0

AccessVector

ADJACENT_NETWORK

Authentication

NONE