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CVE-2021-31371

20
FAUCET Score

CVE-2021-31371 is an information exposure vulnerability affecting Juniper Networks Junos OS on various QFX5000 Series switches. It allows internal communication packets, containing sensitive configuration details like heartbeats and kernel versions, to egress the switch and potentially leak to the internet. Rated as Medium severity (CVSS 5.3), this vulnerability has a network attack vector with low complexity, requiring no user interaction, and could lead to unauthorized disclosure of information. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 17.3R3-S12CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.1, < 18.1R3-S13CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 18.3, < 18.3R3-S5CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 19.1, < 19.1R3-S6CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 20.2, < 20.2R3-S2CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.81%
Probability of exploitation in next 30 days
EPSS Percentile
53.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0081 is in the 33rd percentile among its peer group of 23,725 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

Remediation

Vendor Patches (1)

juniperworkaround availablevia nvd_reference
View patch

References

kb.juniper.net / JSA11236
MitigationVendor Advisory