How severe is CVE-2021-0266?

CVE-2021-0266 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-0266 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-0266?

CVE-2021-0266 primarily affects Juniper Junos. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-0266?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-0266 published?

CVE-2021-0266 was published on 2021-04-22 and last updated on 2026-06-17.

CVE-2021-0266

CVE-2021-0266 is a high-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-798.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 7.5
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-798
Affected product: Juniper Junos
Published: 2021-04-22
Last modified: 2026-06-17

Description

The use of multiple hard-coded cryptographic keys in cSRX Series software in Juniper Networks Junos OS allows an attacker to take control of any instance of a cSRX deployment through device management services. This issue affects: Juniper Networks Junos OS on cSRX Series: All versions prior to 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R2.

Frequently asked questions

What is CVE-2021-0266?: The use of multiple hard-coded cryptographic keys in cSRX Series software in Juniper Networks Junos OS allows an attacker to take control of any instance of a cSRX deployment through device management services. This issue affects: Juniper Networks Junos OS on cSRX Series: All versions prior to 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R2.
How severe is CVE-2021-0266?: CVE-2021-0266 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-0266 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-0266?: CVE-2021-0266 primarily affects Juniper Junos. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-0266?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-0266 published?: CVE-2021-0266 was published on 2021-04-22 and last updated on 2026-06-17.

References

https://kb.juniper.net/JSA11157

Affected products (8)

cpe:2.3:o:juniper:junos:20.2:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.2:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.2:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.2:r1-s3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.3:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.3:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.4:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:20.4:r1-s1:*:*:*:*:*:*

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