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Fencer Vulns
high 8.8

CVE-2018-0021 json

Junos OS: Short MacSec keys may allow man-in-the-middle attacks.

published 2018-04-11 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-0846

cvss
8.8
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

If all 64 digits of the connectivity association name (CKN) key or all 32 digits of the connectivity association key (CAK) key are not configured, all remaining digits will be auto-configured to 0. Hence, Juniper devices configured with short MacSec keys are at risk to an increased likelihood that an attacker will discover the secret passphrases configured for these keys through dictionary-based and brute-force-based attacks using spoofed packets. Affected releases are Juniper Networks Junos OS: 14.1 versions prior to 14.1R10, 14.1R9; 14.1X53 versions prior to 14.1X53-D47; 15.1 versions prior to 15.1R4-S9, 15.1R6-S6, 15.1R7; 15.1X49 versions prior to 15.1X49-D100; 15.1X53 versions prior to 15.1X53-D59; 16.1 versions prior to 16.1R3-S8, 16.1R4-S8, 16.1R5; 16.2 versions prior to 16.2R1-S6, 16.2R2; 17.1 versions prior to 17.1R2.

Patch / fix

  • Juniper Networks Junos OS 14.1R10, 14.1R9, 14.1X53-D47, 15.1R4-S9, 15.1R6-S6, 15.1R7, 15.1X49-D100, 15.1X53-D59, 16.1R3-S8, 16.1R4-S8, 16.1R5, 16.2R1-S6, 16.2R2, 17.1R2

Exploit prediction

0.60% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 8.8 CVSS:3.0/AV:A/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD 3.0 8.8 CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 3.3 AV:A/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • Juniper Networks Junos OS

References

Sources

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.