Junos OS: QFX Series: The PFE may crash when a lot of MAC addresses are being learned and aged

published 2023-04-17 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-32602

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits: 0; none known

A Use After Free vulnerability in the Layer 2 Address Learning Manager (l2alm) of Juniper Networks Junos OS on QFX Series allows an adjacent attacker to cause the Packet Forwarding Engine to crash and restart, leading to a Denial of Service (DoS). The PFE may crash when a lot of MAC learning and aging happens, but due to a Race Condition (Concurrent Execution using Shared Resource with Improper Synchronization) that is outside the attackers direct control. This issue affects: Juniper Networks Junos OS versions prior to 19.4R3-S10 on QFX Series; 20.2 versions prior to 20.2R3-S7 on QFX Series; 20.3 versions prior to 20.3R3-S6 on QFX Series; 20.4 versions prior to 20.4R3-S5 on QFX Series; 21.1 versions prior to 21.1R3-S4 on QFX Series; 21.2 versions prior to 21.2R3-S3 on QFX Series; 21.3 versions prior to 21.3R3-S3 on QFX Series; 21.4 versions prior to 21.4R3 on QFX Series; 22.1 versions prior to 22.1R3 on QFX Series; 22.2 versions prior to 22.2R2 on QFX Series.

Patch / fix

fixed in 1

Juniper Networks Junos OS 19.4R3-S10, 20.2R3-S7, 20.3R3-S6, 20.4R3-S5, 21.1R3-S4, 21.2R3-S3, 21.3R3-S3, 21.4R3, 22.1R3, 22.2R2

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 21 mo ago (2025-02-05)

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.3	CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Juniper Networks Junos OS

Classification

Weakness

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
CWE-416 Use After Free

References

supportportal.juniper.net /JSA70610
vendor-advisory

Sources

CVE List CVE-2023-28984
NVD CVE-2023-28984

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