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CVE-2021-0266

30
FAUCET Score

CVE-2021-0266 describes a critical vulnerability in Juniper Networks Junos OS on cSRX Series software, stemming from the use of multiple hard-coded cryptographic keys. This flaw allows an unauthenticated attacker to gain full control over any cSRX instance via device management services. With a CVSS score of 9.8 (Critical), the vulnerability poses a significant risk due to its network-based attack vector, low attack complexity, and high impact on confidentiality, integrity, and availability. While no public exploit code or active exploitation has been observed, and community discussion is minimal, the inherent severity warrants immediate patching for affected versions prior to 20.2R3, 20.3R2, and 20.4R2.

Impacted Technologies

VendorProductVersion(s)CPE
< 20.2R3CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 20.3, < 20.3R2CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
>= 20.4, < 20.4R2CPE match
cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
20.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:20.2:r1:*:*:*:*:*:*
20.2CPE matchmatch criteria
cpe:2.3:o:juniper:junos:20.2:r1-s1:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.88%
Probability of exploitation in next 30 days
EPSS Percentile
55.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0088 is in the 40th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 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 / JSA11157
Vendor Advisory