CVE intelligence and bounded remediation

CVE-2021-0266 — Juniper Junos security vulnerability

Critical CVSS 9.8

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.

Severity
Critical
CVSS
9.8 (3.1)
Published
2021-04-22
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-321, CWE-798

Affected products

  • juniper / junos / 20.2
  • juniper / junos / 20.3
  • juniper / junos / 20.4

Showing 3 representative product identities from 8 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

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Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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