Junos OS: A crafted Ethernet OAM packet received by Junos may cause the Ethernet OAM connectivity fault management process (CFM) to core.

published 2020-04-08 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-12505

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.1%; EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits: 0; none known

When an attacker sends a specific crafted Ethernet Operation, Administration, and Maintenance (Ethernet OAM) packet to a target device, it may improperly handle the incoming malformed data and fail to sanitize this incoming data resulting in an overflow condition. This overflow condition in Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) condition by coring the CFM daemon. Continued receipt of these packets may cause an extended Denial of Service condition. This issue affects: Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S15; 12.3X48 versions prior to 12.3X48-D95 on SRX Series; 14.1X50 versions prior to 14.1X50-D145; 14.1X53 versions prior to 14.1X53-D47; 15.1 versions prior to 15.1R2; 15.1X49 versions prior to 15.1X49-D170 on SRX Series; 15.1X53 versions prior to 15.1X53-D67.

Patch / fix

fixed in 1

Juniper Networks Junos OS 12.3R12-S15, 12.3X48-D95, 14.1X50-D145, 14.1X53-D47, 15.1R2, 15.1X49-D170, 15.1X53-D67

Exploit prediction

1.09% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

Juniper Networks Junos OS

Classification

Weakness

CWE-703 Improper Check or Handling of Exceptional Conditions
CWE-755 Improper Handling of Exceptional Conditions

References

kb.juniper.net /
vendor-advisory

Sources

CVE List CVE-2020-1639
NVD CVE-2020-1639

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