Junos OS: MX Series with SPC3 line card: Port flaps causes rtlogd memory leak leading to Denial of Service

published 2024-07-11 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-38076

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits: 0; none known

A Missing Release of Memory after Effective Lifetime vulnerability in the rtlogd process of Juniper Networks Junos OS on MX Series with SPC3 allows an unauthenticated, adjacent attacker to trigger internal events cause ( which can be done by repeated port flaps) to cause a slow memory leak, ultimately leading to a Denial of Service (DoS).

Memory can only be recovered by manually restarting rtlogd process. The memory usage can be monitored using the below command.

user@host> show system processes extensive | match rtlog

This issue affects Junos OS on MX Series with SPC3 line card:

* from 21.2R3 before 21.2R3-S8, * from 21.4R2 before 21.4R3-S6, * from 22.1 before 22.1R3-S5, * from 22.2 before 22.2R3-S3, * from 22.3 before 22.3R3-S2, * from 22.4 before 22.4R3-S1, * from 23.2 before 23.2R2, * from 23.4 before 23.4R2.

Patch / fix

fixed in 1

Juniper Networks Junos OS 21.2R3-S8, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, 22.4R3-S1, 23.2R2, 23.4R2

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-07-11)

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA	4.0	7.1	CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/R:U
CNA	4.0	7.1	CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:X/RE:X/U:X

Affected products

Juniper Networks Junos OS

Classification

Weakness

CWE-401 Missing Release of Memory after Effective Lifetime

References

supportportal.juniper.net /JSA83012
vendor-advisory

Sources

CVE List CVE-2024-39550
NVD CVE-2024-39550

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary