CVE-2021-0295

Junos OS: QFX10K Series: Denial of Service (DoS) upon receipt of DVMRP packets received on multi-homing ESI in VXLAN.

Description

A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) of Juniper Networks Junos OS on the QFX10K Series switches allows an attacker to trigger a packet forwarding loop, leading to a partial Denial of Service (DoS). The issue is caused by DVMRP packets looping on a multi-homed Ethernet Segment Identifier (ESI) when VXLAN is configured. DVMRP packets received on a multi-homed ESI are sent to the peer, and then incorrectly forwarded out the same ESI, violating the split horizon rule. This issue only affects QFX10K Series switches, including the QFX10002, QFX10008, and QFX10016. Other products and platforms are unaffected by this vulnerability. This issue affects Juniper Networks Junos OS on QFX10K Series: 17.3 versions prior to 17.3R3-S12; 17.4 versions prior to 17.4R3-S5; 18.1 versions prior to 18.1R3-S13; 18.2 version 18.2R1 and later versions; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S9, 18.4R3-S8; 19.1 versions prior to 19.1R3-S5; 19.2 versions prior to 19.2R1-S7, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R3-S3; 20.1 versions prior to 20.1R2-S2, 20.1R3; 20.2 versions prior to 20.2R3; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2.

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S12, 17.4R3-S5, 18.1R3-S13, 18.3R3-S5, 18.4R2-S9, 18.4R3-S8, 19.1R3-S5, 19.2R1-S7, 19.2R3-S2, 19.3R3-S2, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R3, 20.3R3, 20.4R2, 21.1R1, and all subsequent releases.

Workaround:

  • There are no viable workarounds for this issue. Service may be temporarily restored by disabling/enabled the IRB affected by this issue. Note that this will cause a temporary service interruption as the interface is flapped.

Category

6.1
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.11%
Vendor Advisory juniper.net
Affected: Juniper Networks Junos OS
Published at:
Updated at:

References

Link Tags
https://kb.juniper.net/JSA11208 vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-0295?
CVE-2021-0295 has been scored as a medium severity vulnerability.
How to fix CVE-2021-0295?
To fix CVE-2021-0295: The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S12, 17.4R3-S5, 18.1R3-S13, 18.3R3-S5, 18.4R2-S9, 18.4R3-S8, 19.1R3-S5, 19.2R1-S7, 19.2R3-S2, 19.3R3-S2, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R3, 20.3R3, 20.4R2, 21.1R1, and all subsequent releases.
Is CVE-2021-0295 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-0295 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-0295?
CVE-2021-0295 affects Juniper Networks Junos OS.
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