Junos OS: A low privileged user can escalate their privileges so that they can login as root
Summary
| CVE | CVE-2026-21916 |
|---|---|
| State | PUBLISHED |
| Assigner | juniper |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-09 22:16:24 UTC |
| Updated | 2026-04-17 18:05:52 UTC |
| Description | A UNIX Symbolic Link (Symlink) Following vulnerability in the CLI of Juniper Networks Junos OS allows a local, authenticated attacker with low privileges to escalate their privileges to root which will lead to a complete compromise of the system. When after a user has performed a specific 'file link ...' CLI operation, another user commits (unrelated configuration changes), the first user can login as root. This issue affects Junos OS: * all versions before 23.2R2-S7, * 23.4 versions before 23.4R2-S6, * 24.2 versions before 24.2R2-S3, * 24.4 versions before 24.4R2-S2, * 25.2 versions before 25.2R2. This issue does not affect versions 25.4R1 or later. |
Risk And Classification
Primary CVSS: v4.0 7 HIGH from [email protected]
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:X/RE:M/U:X
EPSS: 0.000120000 probability, percentile 0.017970000 (date 2026-04-21)
Problem Types: CWE-61 | CWE-61 CWE-61 UNIX Symbolic Link (Symlink) Following
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 7 | HIGH | CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/E:X/C... |
| 4.0 | CNA | CVSS | 7 | HIGH | CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/AU:Y/... |
| 3.1 | [email protected] | Primary | 7.3 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 7.3 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H |
CVSS v4.0 Breakdown
Attack Vector
LocalAttack Complexity
LowAttack Requirements
NonePrivileges Required
LowUser Interaction
PassiveConfidentiality
HighIntegrity
HighAvailability
HighSub Conf.
NoneSub Integrity
NoneSub Availability
LowCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:X/RE:M/U:X
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
LowUser Interaction
RequiredScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Juniper | Junos | All | All | All | All |
| Operating System | Juniper | Junos | 23.2 | - | All | All |
| Operating System | Juniper | Junos | 23.2 | r1 | All | All |
| Operating System | Juniper | Junos | 23.2 | r1-s1 | All | All |
| Operating System | Juniper | Junos | 23.2 | r1-s2 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2-s1 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2-s2 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2-s3 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2-s4 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2-s5 | All | All |
| Operating System | Juniper | Junos | 23.2 | r2-s6 | All | All |
| Operating System | Juniper | Junos | 23.4 | - | All | All |
| Operating System | Juniper | Junos | 23.4 | r1 | All | All |
| Operating System | Juniper | Junos | 23.4 | r1-s1 | All | All |
| Operating System | Juniper | Junos | 23.4 | r1-s2 | All | All |
| Operating System | Juniper | Junos | 23.4 | r2 | All | All |
| Operating System | Juniper | Junos | 23.4 | r2-s1 | All | All |
| Operating System | Juniper | Junos | 23.4 | r2-s2 | All | All |
| Operating System | Juniper | Junos | 23.4 | r2-s3 | All | All |
| Operating System | Juniper | Junos | 23.4 | r2-s4 | All | All |
| Operating System | Juniper | Junos | 23.4 | r2-s5 | All | All |
| Operating System | Juniper | Junos | 24.2 | - | All | All |
| Operating System | Juniper | Junos | 24.2 | r1 | All | All |
| Operating System | Juniper | Junos | 24.2 | r1-s1 | All | All |
| Operating System | Juniper | Junos | 24.2 | r1-s2 | All | All |
| Operating System | Juniper | Junos | 24.2 | r2 | All | All |
| Operating System | Juniper | Junos | 24.2 | r2-s1 | All | All |
| Operating System | Juniper | Junos | 24.2 | r2-s2 | All | All |
| Operating System | Juniper | Junos | 24.4 | - | All | All |
| Operating System | Juniper | Junos | 24.4 | r1 | All | All |
| Operating System | Juniper | Junos | 24.4 | r1-s2 | All | All |
| Operating System | Juniper | Junos | 24.4 | r1-s3 | All | All |
| Operating System | Juniper | Junos | 24.4 | r2 | All | All |
| Operating System | Juniper | Junos | 24.4 | r2-s1 | All | All |
| Operating System | Juniper | Junos | 25.2 | - | All | All |
| Operating System | Juniper | Junos | 25.2 | r1 | All | All |
| Operating System | Juniper | Junos | 25.2 | r1-s1 | All | All |
| Operating System | Juniper | Junos | 25.2 | r1-s2 | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Juniper Networks | Junos OS | affected 23.2R2-S7 semver | Not specified |
| CNA | Juniper Networks | Junos OS | affected 23.4 23.4R2-S6 semver | Not specified |
| CNA | Juniper Networks | Junos OS | affected 24.2 24.2R2-S3 semver | Not specified |
| CNA | Juniper Networks | Junos OS | affected 24.4 24.4R2-S2 semver | Not specified |
| CNA | Juniper Networks | Junos OS | affected 25.2 25.2R2 semver | Not specified |
| CNA | Juniper Networks | Junos OS | unaffected 25.4R1 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| kb.juniper.net/JSA107807 | [email protected] | kb.juniper.net | Mitigation, Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
Additional Advisory Data
Solutions
CNA: The following software releases have been updated to resolve this specific issue: 23.2R2-S7, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2, 25.2R2, and all subsequent releases.
Workarounds
CNA: To prevent exploitation, use access controls to keep users from performing 'file link' operations.
Exploits
CNA: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
There are currently no legacy QID mappings associated with this CVE.