CVE-2023-4481

Junos OS and Junos OS Evolved: A crafted BGP UPDATE message allows a remote attacker to de-peer (reset) BGP sessions (CVE-2023-4481)

Description

An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS). When certain specific crafted BGP UPDATE messages are received over an established BGP session, one BGP session may be torn down with an UPDATE message error, or the issue may propagate beyond the local system which will remain non-impacted, but may affect one or more remote systems. This issue is exploitable remotely as the crafted UPDATE message can propagate through unaffected systems and intermediate BGP speakers. Continuous receipt of the crafted BGP UPDATE messages will create a sustained Denial of Service (DoS) condition for impacted devices. This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations. This issue requires a remote attacker to have at least one established BGP session. Improper Input Validation, Denial of Service vulnerability in Juniper Networks, Inc. Junos OS (BGP, rpd modules), Juniper Networks, Inc. Junos OS Evolved (BGP, rpd modules) allows Fuzzing.This issue affects  Junos OS:  * All versions before 20.4R3-S10, * from 21.1R1 through 21.*, * from 21.2 before 21.2R3-S5, * from 21.3 before 21.3R3-S5, * from 21.4 before 21.4R3-S7 (unaffected from 21.4R3-S5, affected from 21.4R3-S6) * from 22.1 before 22.1R3-S4, * from 22.2 before 22.2R3-S3, * from 22.3 before 22.3R3-S1, * from 22.4 before 22.4R3, * from 23.2 before 23.2R2. Junos OS Evolved: * All versions before 20.4R3-S10-EVO, * from 21.2-EVO before 21.2R3-S7-EVO, * from 21.3-EVO before 21.3R3-S5-EVO, * from 21.4-EVO before 21.4R3-S5-EVO, * from 22.1-EVO before 22.1R3-S4-EVO, * from 22.2-EVO before 22.2R3-S3-EVO, * from 22.3-EVO before 22.3R3-S1-EVO, * from 22.4-EVO before 22.4R3-EVO, * from 23.2-EVO before 23.2R2-EVO.

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: Junos OS: 20.4R3-S10, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5 or 21.4R3-S7, 22.1R3-S4, 22.2R3-S3, 22.3R3-S1, 22.4R3, 23.2R2, 23.3R2, 23.4R1, and all subsequent releases Note: except for Junos OS 21.4R3-S6 which is affected and unfixed. Junos OS Evolved: 20.4R3-S10-EVO, 21.2R3-S7-EVO, 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S3-EVO, 22.3R3-S1-EVO, 22.4R3-EVO, 23.2R2-EVO, 23.4R1-EVO, and all subsequent releases. It is important that customers implement the workaround in addition to taking any updated software as these crafted UPDATE messages may be propagated to other devices even if non-impacted locally, thereby protecting the network by stopping the propagation of these crafted UPDATE messages. The workaround is to configure BGP error tolerance by way of:   [ protocols bgp bgp-error-tolerance ... ] Additional details can be found at https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h... https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html Juniper considers configuring this option to be a Best Common Practice (BCP) as it not only prevents this issue from happening, but protects against similar issues as well. This issue is being tracked as PR 1709837 https://prsearch.juniper.net/problemreport/PR1709837  which is visible on the Customer Support website. Note: Juniper SIRT's policy https://kb.juniper.net/KB16765  is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Workaround:

  • The workaround is to configure BGP error tolerance by way of:   [ protocols bgp bgp-error-tolerance ... ] Additional details can be found at https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h... https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html Juniper considers configuring this option to be a Best Common Practice (BCP) as it not only prevents this issue from happening, but protects against similar issues as well.

Category

7.5
CVSS
Severity: High
CVSS 3.1 •
EPSS 1.30% Top 25%
Vendor Advisory juniper.net Vendor Advisory juniper.net
Affected: Juniper Networks, Inc. Junos OS
Affected: Juniper Networks, Inc. Junos OS Evolved
Published at:
Updated at:

References

Link Tags
https://kb.juniper.net/JSA72510 vendor advisory
https://www.rfc-editor.org/rfc/rfc7606 technical description
https://www.rfc-editor.org/rfc/rfc4271 technical description
https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html vendor advisory technical description

Frequently Asked Questions

What is the severity of CVE-2023-4481?
CVE-2023-4481 has been scored as a high severity vulnerability.
How to fix CVE-2023-4481?
To fix CVE-2023-4481: The following software releases have been updated to resolve this specific issue: Junos OS: 20.4R3-S10, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5 or 21.4R3-S7, 22.1R3-S4, 22.2R3-S3, 22.3R3-S1, 22.4R3, 23.2R2, 23.3R2, 23.4R1, and all subsequent releases Note: except for Junos OS 21.4R3-S6 which is affected and unfixed. Junos OS Evolved: 20.4R3-S10-EVO, 21.2R3-S7-EVO, 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S3-EVO, 22.3R3-S1-EVO, 22.4R3-EVO, 23.2R2-EVO, 23.4R1-EVO, and all subsequent releases. It is important that customers implement the workaround in addition to taking any updated software as these crafted UPDATE messages may be propagated to other devices even if non-impacted locally, thereby protecting the network by stopping the propagation of these crafted UPDATE messages. The workaround is to configure BGP error tolerance by way of:   [ protocols bgp bgp-error-tolerance ... ] Additional details can be found at https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h... https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html Juniper considers configuring this option to be a Best Common Practice (BCP) as it not only prevents this issue from happening, but protects against similar issues as well. This issue is being tracked as PR 1709837 https://prsearch.juniper.net/problemreport/PR1709837  which is visible on the Customer Support website. Note: Juniper SIRT's policy https://kb.juniper.net/KB16765  is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).
Is CVE-2023-4481 being actively exploited in the wild?
It is possible that CVE-2023-4481 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~1% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2023-4481?
CVE-2023-4481 affects Juniper Networks, Inc. Junos OS, Juniper Networks, Inc. Junos OS Evolved.
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