CVE-2026-21916 PUBLISHED

Junos OS: A low privileged user can escalate their privileges so that they can login as root

Assigner: juniper
Reserved: 05.01.2026 Published: 09.04.2026 Updated: 10.04.2026

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.

Metrics

CVSS Vector: 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/R:U/RE:M
CVSS Score: 7

Product Status

Vendor Juniper Networks
Product Junos OS
Versions Default: unaffected
  • affected from 0 to 23.2R2-S7 (excl.)
  • affected from 23.4 to 23.4R2-S6 (excl.)
  • affected from 24.2 to 24.2R2-S3 (excl.)
  • affected from 24.4 to 24.4R2-S2 (excl.)
  • affected from 25.2 to 25.2R2 (excl.)
  • Version 25.4R1 is unaffected

Exploits

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

Workarounds

To prevent exploitation, use access controls to keep users from performing 'file link' operations.

Solutions

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.

References

Problem Types

  • CWE-61 UNIX Symbolic Link (Symlink) Following CWE