CVE-2021-0299

Junos OS: Kernel crash (vmcore) upon receipt of a malformed IPv6 packet

HIGH

7.5

CVSS Score

Published: October 19, 2021 at 06:16 PM UTC

Updated: June 17, 2026 at 03:29 AM UTC

1 product affected across 1 vendorJunos

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Severity

HIGH7.5

Exploit prediction

EPSS 1%

Description

An Improper Handling of Exceptional Conditions vulnerability in the processing of a transit or directly received malformed IPv6 packet in Juniper Networks Junos OS results in a kernel crash, causing the device to restart, leading to a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue only affects systems with IPv6 configured. Devices with only IPv4 configured are not vulnerable to this issue. This issue affects Juniper Networks Junos OS: 19.4 versions prior to 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S1, 20.2R2. This issue does not affect Juniper Networks Junos OS versions prior to 19.4R1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

19.4 ≤ v < 19.4R320.1 ≤ v < 20.1R220.2 ≤ v < 20.2R1-S1, 20.2R219.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r1-s3 19.4 r1-s4 19.4 r2 19.4 r2-s1 19.4 r2-s2 19.4 r2-s3 19.4 r2-s4 19.4 r2-s5 20.1 20.1 r1 20.1 r1-s1 20.1 r1-s2 20.1 r1-s3 20.1 r1-s4 20.2 20.2 r1

Vendor states this is fixed in 19.4R1 (unaffected)

Affected range stops below 19.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R1-S1, 20.2R2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://kb.juniper.net/JSA11213

References (1)

x_refsource_CONFIRMVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11213

CVSS

7.5HIGHjuniper

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-755

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