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CVE-2025-21590

Junos OS: An local attacker with shell access can execute arbitrary code

Exploited in the wild. In CISA KEV since 2025‑03‑13. Fixed versions are out.

CVSS 3.14.4MediumEPSS percentile77th1.7% chance in 30 daysCISA KEVListedsince 2025-03-13, due 2025-04-03
Public exploit: 0 sourcesFix2 products5 fixed builds listed below

Published Updated Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Juniper Networks Junos OSAffected: < 21.2R3-S9Upgrade to: 21.2R3-S9Affected: ≥ 21.4, < 21.4R3-S10Upgrade to: 21.4R3-S10Affected: ≥ 22.2, < 22.2R3-S6Upgrade to: 22.2R3-S6Affected: ≥ 22.4, < 22.4R3-S6Upgrade to: 22.4R3-S6 + 4 more branchesStated by: CVE record
  • Juniper JunosAffected: < 21.2Upgrade to: 21.2Stated by: NVD

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

Coverage timeline

0 publishers

  1. Added to CISA KEV catalog

    ·CISA KEV

Sourced from public security reporting — each date is when it was published, not when it happened. 1 further article named this CVE in wider roundups without reporting it as a distinct event.

What it is

From the CVE record

An Improper Isolation or Compartmentalization vulnerability in the kernel of Juniper Networks Junos OS allows a local attacker with high privileges to compromise the integrity of the device. A local attacker with access to the shell is able to inject arbitrary code which can compromise an affected device. This issue is not exploitable from the Junos CLI. This issue affects Junos OS:  * All versions before 21.2R3-S9, * 21.4 versions before 21.4R3-S10,  * 22.2 versions before 22.2R3-S6,  * 22.4 versions before 22.4R3-S6,  * 23.2 versions before 23.2R2-S3,  * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R1-S2, 24.2R2.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS77th
Public exploit
CISA KEV
CISA KEV

Listed as exploited in the wild since 2025-03-13.

US federal agencies must remediate by 2025-04-03.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Public exploits

0 sources with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

1.7% chance of exploitation activity in the next 30 days, which ranks it in the 77th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Attention now

Rising.

Lifecycle

10 events over 568 days, from the signal feeds we watch.

  1. Patch availableworkaround available, record updated
  2. OpenVAS check added
  3. Patch availableworkaround available, record updated
  4. Added to CISA KEV
  5. Publishedweakness classified

Affected products

And 1 more affected product. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

Scored 4.4 by NVD.

How it is reached

  • Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required HighRequires admin or elevated privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality NoneNo confidentiality impact
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability NoneNo availability impact

Weaknesses

Sources

References in the record

And 2 more references. See all after sign-in

In the news

Watch the software you run.

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We'll flag the next CVE, public exploit or patch for JunOS, not every advisory. This one: actively exploited.