CVE-2023-44186

Junos OS and Junos OS Evolved: RPD crash when attempting to send a very long AS PATH to a non-4-byte-AS capable BGP neighbor

Description

An Improper Handling of Exceptional Conditions vulnerability in AS PATH processing of Juniper Networks Junos OS and Junos OS Evolved allows an attacker to send a BGP update message with an AS PATH containing a large number of 4-byte ASes, leading to a Denial of Service (DoS). Continued receipt and processing of these BGP updates will create a sustained Denial of Service (DoS) condition. This issue is hit when the router has Non-Stop Routing (NSR) enabled, has a non-4-byte-AS capable BGP neighbor, receives a BGP update message with a prefix that includes a long AS PATH containing large number of 4-byte ASes, and has to advertise the prefix towards the non-4-byte-AS capable BGP neighbor. Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability. This issue affects: Juniper Networks Junos OS: * All versions prior to 20.4R3-S8; * 21.1 versions 21.1R1 and later; * 21.2 versions prior to 21.2R3-S6; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S5; * 22.1 versions prior to 22.1R3-S4; * 22.2 versions prior to 22.2R3-S2; * 22.3 versions prior to 22.3R2-S2, 22.3R3-S1; * 22.4 versions prior to 22.4R2-S1, 22.4R3. Juniper Networks Junos OS Evolved * All versions prior to 20.4R3-S8-EVO; * 21.1 versions 21.1R1-EVO and later; * 21.2 versions prior to 21.2R3-S6-EVO; * 21.3 versions prior to 21.3R3-S5-EVO; * 21.4 versions prior to 21.4R3-S5-EVO; * 22.1 versions prior to 22.1R3-S4-EVO; * 22.2 versions prior to 22.2R3-S2-EVO; * 22.3 versions prior to 22.3R2-S2-EVO, 22.3R3-S1-EVO; * 22.4 versions prior to 22.4R2-S1-EVO, 22.4R3-EVO.

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: Junos OS: 20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2, 22.3R3-S1, 22.4R2-S1, 22.4R3, 23.2R1, and all subsequent releases. Junos OS Evolved: 20.4R3-S8-EVO, 21.2R3-S6-EVO, 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S2-EVO, 22.3R2-S2-EVO, 22.3R3-S1-EVO, 22.4R2-S1-EVO, 22.4R3-EVO, 23.2R1-EVO, and all subsequent releases.

Workaround:

  • Current operational and security best practices, such as limiting the AS PATH length, should mitigate risk of this issue. Below is an example configuration to limit AS PATH to 30 entries: set groups BASE-POLICY policy-options policy-statement MaxAS-Limit-30 term more-than-30 from protocol bgp set groups BASE-POLICY policy-options policy-statement MaxAS-Limit-30 term more-than-30 from as-path 31as set groups BASE-POLICY policy-options policy-statement MaxAS-Limit-30 term more-than-30 then reject set groups BASE-POLICY policy-options policy-statement MaxAS-Limit-30 then accept set groups BASE-POLICY policy-options policy-statement Customer-IN term MaxAS-Limit from policy MaxAS-Limit-30 set groups BASE-BGP protocols bgp group <*-CUSTOMER> import Customer-IN set groups BASE-PREFIX-LISTS policy-options as-path 31as ".{31,}"

Category

7.5
CVSS
Severity: High
CVSS 3.1 •
EPSS 0.15%
Vendor Advisory juniper.net
Affected: Juniper Networks Junos OS
Affected: Juniper Networks Junos OS Evolved
Published at:
Updated at:

References

Link Tags
https://supportportal.juniper.net/JSA73150 mitigation vendor advisory

Frequently Asked Questions

What is the severity of CVE-2023-44186?
CVE-2023-44186 has been scored as a high severity vulnerability.
How to fix CVE-2023-44186?
To fix CVE-2023-44186: The following software releases have been updated to resolve this specific issue: Junos OS: 20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2, 22.3R3-S1, 22.4R2-S1, 22.4R3, 23.2R1, and all subsequent releases. Junos OS Evolved: 20.4R3-S8-EVO, 21.2R3-S6-EVO, 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S2-EVO, 22.3R2-S2-EVO, 22.3R3-S1-EVO, 22.4R2-S1-EVO, 22.4R3-EVO, 23.2R1-EVO, and all subsequent releases.
Is CVE-2023-44186 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2023-44186 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-2023-44186?
CVE-2023-44186 affects Juniper Networks Junos OS, Juniper Networks Junos OS Evolved.
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