CVE-2026-21916
Symlink Following Vulnerability in Junos OS Enables Root Escalation
Publication date: 2026-04-09
Last updated on: 2026-04-17
Assigner: Juniper Networks, Inc.
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| juniper | junos | 23.2 |
| juniper | junos | 23.2 |
| juniper | junos | 23.2 |
| juniper | junos | 23.2 |
| juniper | junos | 23.4 |
| juniper | junos | 23.4 |
| juniper | junos | 23.4 |
| juniper | junos | 23.2 |
| juniper | junos | 24.2 |
| juniper | junos | 24.2 |
| juniper | junos | 23.4 |
| juniper | junos | 23.2 |
| juniper | junos | 23.2 |
| juniper | junos | 23.4 |
| juniper | junos | 23.4 |
| juniper | junos | 23.4 |
| juniper | junos | 23.4 |
| juniper | junos | 24.2 |
| juniper | junos | 24.2 |
| juniper | junos | 23.2 |
| juniper | junos | 23.2 |
| juniper | junos | 23.4 |
| juniper | junos | 24.2 |
| juniper | junos | 24.4 |
| juniper | junos | 24.4 |
| juniper | junos | 24.4 |
| juniper | junos | 24.4 |
| juniper | junos | 24.2 |
| juniper | junos | 24.4 |
| juniper | junos | 23.4 |
| juniper | junos | 24.2 |
| juniper | junos | 24.4 |
| juniper | junos | 25.2 |
| juniper | junos | 25.2 |
| juniper | junos | 25.2 |
| juniper | junos | 25.2 |
| juniper | junos | 23.2 |
| juniper | junos | to 23.2 (exc) |
| juniper | junos | 23.2 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-61 | The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. |
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability impact me? :
The vulnerability can lead to a complete compromise of the affected system. A low-privileged local user can escalate their privileges to root, gaining full control over the system. This can result in unauthorized access, modification, or destruction of data, disruption of services, and potential further exploitation of the network or connected systems.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade your Junos OS to a version that is not affected by this issue.
- Upgrade to Junos OS version 25.4R1 or later.
- If upgrading immediately is not possible, restrict local authenticated user access to prevent exploitation.
Can you explain this vulnerability to me?
This vulnerability is a UNIX Symbolic Link (Symlink) Following issue in the command-line interface (CLI) of Juniper Networks Junos OS. It allows a local, authenticated user with low privileges to escalate their privileges to root. The escalation happens when a user performs a specific 'file link ...' CLI operation, and then another user commits unrelated configuration changes. After this sequence, the first user can log in as root, leading to a complete system compromise.