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CVE-2021-0237

22
FAUCET Score

CVE-2021-0237 is a Denial of Service (DoS) vulnerability affecting Juniper Networks EX4300-MP, EX4600, EX4650, and QFX5K Series devices running specific Junos OS versions when configured as a Virtual Chassis with a particular Layer 2 circuit. A remote attacker can trigger a crash and restart of the Packet Forwarding Engine manager (FXPC) process by sending specially crafted Layer 2 frames, leading to a sustained DoS condition. This vulnerability has a CVSS v3.1 score of 6.5 (Medium), indicating an attack vector requiring adjacent network access with low complexity and high impact on availability. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
>= 15.1, < 15.1R7-S9CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 17.3, < 17.3R3-S11CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.2, < 18.2R3-S8CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.3, < 18.3R3-S4CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 19.1, < 19.1R3-S4CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.38%
Probability of exploitation in next 30 days
EPSS Percentile
30.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0038 is in the 46th percentile among its peer group of 1,802 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

junipervendor investigatingvia nvd_reference
View patch

References

kb.juniper.net / JSA11132
Vendor Advisory