CVE-2025-21590KEV · OVERDUECWE-653

Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability

Medium · published March 12, 2025

Patch now

The score understates this — it's already being exploited

CVSS calls it medium at 4.4. It is confirmed in active exploitation. It sits in the 77.5th percentile for exploit probability.

569
days past CISA
deadline
CVSS v3.1
4.4
EPSS
2%
Percentile
77.5
In the wild
Confirmed
What it is

⚠️ A local attacker with high privileges can exploit this vulnerability like a mischievous chef sneaking unauthorized ingredients into a secret recipe! Think of a restaurant where a chef has access to the back room but isn’t supposed to touch the orders. If the chef starts changing the recipes without permission, the entire menu can become compromised! An attacker could inject arbitrary code into the Junos OS, potentially leading to total compromise of the affected device. While the exploits aren't easy to pull off without access, the consequences could still be significant, like a chef changing all the menu items to something unsavory. Imagine the chaos!

Put simply

Think of a restaurant where a chef has access to the back room but isn’t supposed to touch the orders. If the chef starts changing the recipes without permission, the entire menu can become compromised! This improper isolation vulnerability in Junos OS lets a local attacker with high privileges execute arbitrary code, potentially compromising the device's integrity. This flaw is not exploitable from the Junos CLI, but it still poses a risk to affected systems.

What to do

An attacker could inject arbitrary code into the Junos OS, potentially leading to total compromise of the affected device. While the exploits aren't easy to pull off without access, the consequences could still be significant, like a chef changing all the menu items to something unsavory. Imagine the chaos! To mitigate this issue, ensure your Junos OS is upgraded to one of the patched versions: 21.2R3-S9 or later, 21.4R3-S10 or later, and so forth as listed. Regularly check for updates to keep your system secure! You've got this! Stay vigilant, patch up, and you'll be the hero of your network! 🛡️

The record
Technical detail
CVSS v3.1
4.4 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.01735 · 77.5th percentile
Weakness
CWE-653 · Improper Isolation or Compartmentalization
Published
2025-03-12T18:15Z
KEV added
2025-03-13 · due 2025-04-03
Affected products (79)
ProductVersionsFixed in
juniper/junos< 21.221.2
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References (3)
EPSS history
Timeline
  • 13 MAR 00:00Z
    Added to CISA KEV — remediate by Apr 3
    kev
  • 12 MAR 13:59Z
    Junos OS: An local attacker with shell access can execute arbitrary code
    cvelistv5