Security readout for executives and security teams
Plain-English summary
This vulnerability lets a low-privileged local user on affected Juniper NFX Series devices gain higher privileges through the Junos Device Management Daemon. It is high risk because successful exploitation can compromise confidentiality, integrity, and availability, but the source bundle indicates local access is required.
Executive priority
Prioritize remediation for internet-managed or broadly administered NFX environments, especially where many users have device access. This is not described as remote unauthenticated, but compromise of any low-privileged account could become full device compromise.
Technical view
CVE-2021-0253 is a CWE-77 command execution issue in JDMD on Juniper Networks Junos OS for NFX Series. The CVSS 3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, scoring 7.8. Affected trains include 17.2, 18.4, 19.1, 19.2, 19.3, and 19.4 ranges listed by Juniper.
Likely exposure
Exposure is limited to Juniper NFX Series devices running affected Junos OS versions. The bundle states versions before 17.2R1 are not affected and excludes JDMD use with Junos Node Slicing on listed MX platforms.
Exploitation context
The bundle does not identify active exploitation and KEV is false. Exploitation requires local low-privileged access, so risk is highest where device shell access, admin delegation, or compromised credentials exist.
Researcher notes
The evidence is sufficient for affected product, impact, and access requirements. The source bundle has an ambiguous 19.4 wording fragment, so researchers should validate exact fixed releases against Juniper JSA11146 before closing exposure.
Mitigation direction
- Upgrade affected NFX Series devices to Juniper’s fixed releases or later per JSA11146.
- Restrict local and administrative access to trusted users only.
- Review AAA, SSH, and device account hygiene for NFX Series systems.
- Monitor Juniper advisory JSA11146 for any corrected version clarifications.
Validation and detection
- Inventory all Juniper NFX Series devices and installed Junos OS versions.
- Compare versions against affected ranges in CVE-2021-0253 and JSA11146.
- Confirm non-NFX and excluded Junos Node Slicing cases are not misclassified.
- Review local account activity for unexpected privilege changes or command execution.
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
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-77: Command execution behavior lookup
Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-0253 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
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.juniper.net/JSA11146CVE reference · x_refsource_MISC
- https://github.com/orangecertcc/security-research/security/advisories/GHSA-vrf9-cjcp-rwcrCVE 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.
Improper Neutralization of Special Elements used in a Command ('Command Injection')
Improper Neutralization of Special Elements used in a Command ('Command Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.