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JunosOperating system · Juniper

CVE-2025-30647

MEDIUM · 6.5 CVSS v3.1 Published 2025-04-09
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
70/100
Remediation priority · Elevated
No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A Missing Release of Memory after Effective Lifetime vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows an unauthenticated adjacent attacker to cause a Denial-of-Service (DoS). In a subscriber management scenario, login/logout activity triggers a memory leak, and the leaked memory gradually increments and eventually results in a crash.                 user@host> show chassis fpc                                        Temp    CPU Utilization (%)   CPU Utilization (%)   Memory     Utilization (%)                       Slot State       (C)     Total   Interrupt     1min   5min  15min    DRAM (MB)  Heap   Buffer                       2 Online         36       10         0          9     8     9        32768      26         0                                                                                                       This issue affects Junos OS on MX Series: * All versions before 21.2R3-S9 * from 21.4 before 21.4R3-S10 * from 22.2 before 22.2R3-S6 * from 22.4 before 22.4R3-S5 * from 23.2 before 23.2R2-S3 * from 23.4 before 23.4R2-S3 * from 24.2 before 24.2R2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A memory leak vulnerability exists in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series routers. In subscriber management scenarios, login/logout activity triggers a memory leak that gradually increments with each cycle, eventually exhausting memory and causing the device to crash. An unauthenticated adjacent attacker can trigger this DoS condition by causing repeated subscriber login/logout events.

MitigationApply the appropriate Juniper OS patch from the affected version ranges (21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, or 24.2R2 and later). As an interim control, limit adjacent network access to prevent unauthorized subscriber management activity.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:< 21.2= 21.2= 21.4= 22.2= 22.4= 23.2= 23.4= 24.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model
    Run 'show chassis hardware' or 'show system information' to confirm the device is an MX Series router
    Affected if Device is not an MX Series router - this vulnerability only affects MX Series
  2. Check Junos OS version
    Run 'show version' to obtain the installed Junos OS version number
    Affected if Version matches or falls within: < 21.2, 21.2, 21.4, 22.2, 22.4, 23.2, 23.4, or 24.2
  3. Verify subscriber management is enabled
    Run 'show subscribers summary' or check configuration for 'access' or 'subscriber-management' related configs
    Affected if Subscriber management is configured and active - the vulnerability only triggers through subscriber login/logout cycles
  4. Monitor PFE memory usage
    Run 'show chassis pic 0 fpc-slot 0 pfe-statistics memory' or 'show pfe statistics memory' to check current memory consumption
    Affected if Memory usage shows progressive increase or abnormally high utilization over time
  5. Check for crash or memory exhaustion events
    Run 'show system core-dumps' and review system logs (show log messages) for PFE crashes or out-of-memory events
    Affected if Recent crashes or memory exhaustion events correlated with subscriber activity are present

You are affected if you run an affected Junos version on an MX Series router with subscriber management enabled and observe elevated PFE memory usage or crashes correlating with subscriber login/logout activity.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 21.2 or later
Fixed in 21.2
Interim mitigation

Apply the appropriate Juniper OS patch from the affected version ranges (21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, or 24.2R2 and later). As an interim control, limit adjacent network access to prevent unauthorized subscriber management activity.

Recommended fix High confidence

21.2R3-S9 / 21.4R3-S10 / 22.2R3-S6 / 22.4R3-S5 / 23.2R2-S3 / 23.4R2-S3 / 24.2R2 (depending on current branch)

  1. 1. Identify the current Junos OS version on MX Series device using 'show version'
  2. 2. Plan maintenance window as upgrade requires PFE restart
  3. 3. Download the appropriate fixed Junos OS version from Juniper support portal (21.2R3-S9, 21.4R3-S10, 22.2R3-S6, 22.4R3-S5, 23.2R2-S3, 23.4R2-S3, or 24.2R2)
  4. 4. Upload the Junos OS image to the device via SCP/FTP
  5. 5. Run 'request system software add <package> reboot' to install and reboot
  6. 6. After reboot, verify new version with 'show version'
  7. 7. Monitor memory utilization with 'show chassis fpc' to confirm leak is resolved
Caveat PFE will restart during upgrade causing brief traffic interruption; test upgrade in lab first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation6.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,160
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,256.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-30647 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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