An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
All versions prior to 20.4R3-S7;
21.1 version 21.1R1 and later versions;
21.2 versions prior to 21.2R3-S6;
21.3 versions prior to 21.3R3-S5;
21.4 versions prior to 21.4R3-S3;
22.1 versions prior to 22.1R3-S4;
22.2 versions prior to 22.2R3;
22.3 versions prior to 22.3R2-S2;
22.4 versions prior to 22.4R2;
PPPoE can be configured with the following commands:[edit interfaces interface-name]encapsulation ppp-over-ether;tcp-mss is enabled with the following command:[tcp-mss mss-value;]
[edit interfaces interface-name]
encapsulation ppp-over-ether;
[tcp-mss mss-value;]
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
This issue was seen during production usage.
This issue has been assigned CVE-2023-36841.
The following software releases have been updated to resolve this specific issue: Junos OS 20.4R3-S7, 21.2R3-S6, 21.4R3-S3, 22.1R3-S4, 22.2R3, 22.3R2-S2, 22.3R3, 22.4R2, 23.2R1, and all subsequent releases.
This issue is being tracked as PR 1707742 which is visible on the Customer Support website.
Note: Juniper SIRT's policy [juniper.net] is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).
There are no known workarounds for this issue.
2023-10-11: Initial Publication