Security readout for executives and security teams
Plain-English summary
This flaw affects Juniper cSRX firewall deployments running vulnerable Junos OS. Multiple hard-coded cryptographic keys could let an unauthenticated network attacker take control of a cSRX instance through device management services. The CVSS score is 8.1, with high confidentiality, integrity, and availability impact, so exposed management planes should be treated as urgent.
Executive priority
Prioritize remediation for internet-reachable or broadly accessible cSRX management planes. The business risk is full device compromise of security infrastructure, but current source evidence does not confirm active exploitation.
Technical view
CVE-2021-0266 is CWE-321 in Juniper Networks Junos OS for cSRX Series. Affected releases are all versions before 20.2R3, 20.3 before 20.3R2, and 20.4 before 20.4R2. The CVSS vector is AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H, with high attack complexity but no required privileges.
Likely exposure
Exposure is limited to Juniper cSRX Series deployments running the affected Junos OS releases, especially where device management services are reachable from untrusted networks. The source bundle does not identify other Juniper products as affected.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The vulnerability is remotely reachable through management services and has severe potential impact, but the CVSS vector marks attack complexity high.
Researcher notes
The key facts are vendor/product scoped: cSRX Series Junos OS only, hard-coded cryptographic keys, management-service attack path, and fixed version thresholds. Evidence is incomplete for exploitation in the wild, workarounds, and detection indicators.
Mitigation direction
- Upgrade cSRX Junos OS to 20.2R3, 20.3R2, 20.4R2, or later fixed releases.
- Check Juniper JSA11157 for any current vendor-specific remediation guidance.
- Restrict management service access to trusted administrative networks only.
- Review firewall and access-control policies protecting cSRX management interfaces.
- Monitor management-plane logs for unexpected administrative access or configuration changes.
Validation and detection
- Inventory all Juniper cSRX deployments and record Junos OS versions.
- Confirm no cSRX instance runs versions before the fixed release thresholds.
- Identify which device management services are enabled and reachable.
- Verify management interfaces are not exposed to untrusted networks.
- After upgrade, confirm the reported Junos OS version matches the intended fixed release.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-321: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-0266 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.juniper.net/JSA11157CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Hard-coded Cryptographic Key
Use of Hard-coded Cryptographic Key represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.