What is CVE-2021-0266?

CVE-2021-0266 is a high-severity vulnerability in Juniper Csrx, classified under Use of Hard-coded Cryptographic Key. CVSS score: 8.1/10. Published 2021-04-22.

How severe is CVE-2021-0266?

High severity. CVSS v3 base score is 8.1 out of 10.

Vulnerability in Juniper Csrx

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.

Published 2021-04-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (59.1th percentile), scored 2026-11-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 59.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Juniper Csrx
Juniper Junos — versions 20.2, 20.3, 20.4
Juniper Networks Junos OS — versions unspecified, 20.3, 20.4

Weakness classification (CWE)

References

kb.juniper.net/JSA11157 (Vendor Advisory)

Frequently asked questions

What is CVE-2021-0266?: CVE-2021-0266 is a high-severity vulnerability in Juniper Csrx, classified under Use of Hard-coded Cryptographic Key. CVSS score: 8.1/10. Published 2021-04-22.
How severe is CVE-2021-0266?: High severity. CVSS v3 base score is 8.1 out of 10.