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Product Affected

This issue affects Junos OS Evolved from 23.2R1-EVO, 23.4-EVO, 24.2-EVO, 24.4-EVO. Affected platforms: PTX10001-36MR, PTX10002-36QDD, PTX10004, PTX10008, PTX10016.

Severity

Medium

Severity Assessment (CVSS) Score

CVSS: v3.1: 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVSS: v4.0: 8.3 (CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/AU:Y/R:A/V:C/RE:M/U:Green)

Problem

An Uncontrolled Resource Consumption vulnerability in the Connectivity Fault Management (CFM) daemon and the Connectivity Fault Management Manager (cfmman) of Juniper Networks Junos OS Evolved on PTX10001-36MR, PTX10002-36QDD, PTX10004, PTX10008, PTX10016 allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS).

An attacker on an adjacent device sending specific valid traffic can cause cfmd to spike the CPU to 100% and cfmman's memory to leak, eventually to cause the FPC crash and restart.

Continued receipt and processes of these specific valid packets will sustain the Denial of Service (DoS) condition.

An indicator of compromise is to watch for an increase in cfmman memory rising over time by issuing the following command and evaluating the RSS number. If the RSS is growing into GBs then consider restarting the device to temporarily clear memory.

user@device> show system processes node fpc<num> detail | match cfmman
Example:

show system processes node fpc0 detail | match cfmman F S UID PID PPID PGID SID C PRI NI ADDR SZ WCHAN RSS PSR STIME TTY TIME CMD 4 S root 15204 1 15204 15204 0 80 0 - 90802 - 113652 4 Sep25 ? 00:15:28 /usr/bin/cfmman -p /var/pfe -o -c /usr/conf/cfmman-cfg-active.xml

This issue affects Junos OS Evolved on PTX10001-36MR, PTX10002-36QDD, PTX10004, PTX10008, PTX10016:

from 23.2R1-EVO before 23.2R2-S4-EVO,
from 23.4 before 23.4R2-S4-EVO,
from 24.2 before 24.2R2-EVO,
from 24.4 before 24.4R1-S2-EVO, 24.4R2-EVO.

This issue does not affect Junos OS Evolved on PTX10001-36MR, PTX10002-36QDD, PTX10004, PTX10008, PTX10016 before 23.2R1-EVO.

Required configuration for exposure:

This issue occurs only when CFM has been configured on any interface:
[ protocols oam ethernet connectivity-fault-management maintenance-domain <md-name> level <number> ]

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

This issue was seen during production usage.

Solution

The following software releases have been updated to resolve this specific issue:
Junos OS Evolved: 23.2R2-S4-EVO, 23.4R2-S4-EVO, 24.2R2-EVO, 24.4R1-S2-EVO, 24.4R2-EVO, 25.2R1-EVO, and all subsequent releases.

This issue is being tracked as 1856405 which is visible on the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Workaround

There are no known workarounds for this issue.
To reduce the risk of exploitation, enable input and output access control lists (ACLs) and other filtering mechanisms to limit access to the device only from trusted users, hosts and networks.

Severity Assessment

Information for how Juniper Networks uses CVSS can be found at KB 16446 [juniper.net], "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Modification History