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2021-04 Security Bulletin: Junos OS: Kernel panic upon receipt of specific TCPv6 packet on management interface (CVE-2021-0258)

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Article ID: JSA11149 SECURITY_ADVISORIES Last Updated: 16 Apr 2021Version: 3.0
Product Affected:
This issue affects Junos OS 17.2, 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4.
Problem:

A vulnerability in the forwarding of transit TCPv6 packets received on the Ethernet management interface of Juniper Networks Junos OS allows an attacker to trigger a kernel panic, leading to a Denial of Service (DoS). Continued receipt and processing of these transit packets will create a sustained Denial of Service (DoS) condition. This issue only occurs when TCPv6 packets are routed through the management interface. Other transit traffic, and traffic destined to the management interface, are unaffected by this vulnerability.

This issue was introduced as part of a TCP Parallelization feature added in Junos OS 17.2, and affects systems with concurrent network stack enabled. This feature is enabled by default, but can be disabled (see WORKAROUND section below).

This issue affects Juniper Networks Junos OS:

  • 17.2 versions prior to 17.2R3-S4;
  • 17.3 versions prior to 17.3R3-S9;
  • 17.4 versions prior to 17.4R2-S11, 17.4R3-S2;
  • 18.1 versions prior to 18.1R3-S11;
  • 18.2 versions prior to 18.2R3-S5;
  • 18.3 versions prior to 18.3R2-S4, 18.3R3-S3;
  • 18.4 versions prior to 18.4R2-S5, 18.4R3-S4;
  • 19.1 versions prior to 19.1R2-S2, 19.1R3;
  • 19.2 versions prior to 19.2R1-S5, 19.2R2;
  • 19.3 versions prior to 19.3R2-S4, 19.3R3;
  • 19.4 versions prior to 19.4R1-S3, 19.4R2.

This issue does not affect Juniper Networks Junos OS versions prior to 17.2R1.


Any configuration with IPv6 enabled on the management interface is vulnerable to this issue. For example:

[interfaces fxp0 unit 0 family inet6]


Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned CVE-2021-0258.
 

Solution:

The following software releases have been updated to resolve this specific issue: Junos OS 17.2R3-S4, 17.3R3-S9, 17.4R2-S11, 17.4R3-S2, 18.1R3-S11, 18.2R3-S5, 18.3R2-S4, 18.3R3-S3, 18.4R2-S5, 18.4R3-S4, 19.1R2-S2, 19.1R3, 19.2R1-S5, 19.2R2, 19.3R2-S4, 19.3R3, 19.4R1-S3, 19.4R2, 20.1R1, and all subsequent releases.

This issue is being tracked as 1477824.
 

Workaround:

Disable TCP Parallelization:

set system kernel-smp-features disable-concurrent-network-stack
 
Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
 
Modification History:
2021-04-14: Initial Publication.
2021-04-16: Further clarification of Junos OS 17.2 affected releases.


CVSS Score:
5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Medium
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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