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JunosOperating system · Juniper

CVE-2025-30660

HIGH · 7.5 CVSS v3.1 Published 2025-04-09
Fix available
A fix is available. Upgrade to 21.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable 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
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).When processing a high rate of specific GRE traffic destined to the device, the respective PFE will hang causing traffic forwarding to stop. When this issue occurs the following logs can be observed: <fpc #> MQSS(0): LI-3: Received a parcel with more than 512B accompanying data CHASSISD_FPC_ASIC_ERROR: ASIC Error detected <...> This issue affects Junos OS: * all versions before 21.2R3-S9, * 21.4 versions before 21.4R3-S8, * 22.2 versions before 22.2R3-S4, * 22.4 versions before 22.4R3-S5, * 23.2 versions before 23.2R2-S2, * 23.4 versions before 23.4R2.

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 denial-of-service vulnerability exists in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series. An unauthenticated, network-based attacker can trigger the vulnerability by sending a high rate of specific GRE traffic to the device, causing the PFE to hang and stop traffic forwarding. The vulnerability stems from improper handling of unusual conditions when processing GRE packets with more than 512B of accompanying data, leading to an ASIC error.

MitigationUpgrade Junos OS on MX Series devices to the fixed versions: 21.2R3-S9, 21.4R3-S8, 22.2R3-S4, 22.4R3-S5, 23.2R2-S2, or 23.4R2 or later. If immediate patching is not possible, consider filtering or rate-limiting GRE traffic destined to the device as a temporary mitigation.

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

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/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. Confirm device is an MX Series platform
    Run 'show chassis hardware' or 'show system information' and verify the hardware model is from the MX Series product line
    Affected if The device is NOT an MX Series router, as this vulnerability only affects MX Series devices
  2. Identify the installed Junos OS version
    Run 'show version' or 'show system information' to retrieve the exact Junos OS version running on the device
    Affected if The installed version matches one of the affected versions: any version below 21.2, or exactly 21.2, 21.4, 22.2, 22.4, 23.2, or 23.4
  3. Check if GRE interfaces are configured
    Run 'show configuration | display set | match gre' to search for any GRE tunnel interfaces in the configuration
    Affected if GRE interfaces are configured, as the vulnerability is triggered by GRE packet processing
  4. Verify if the device is receiving GRE traffic
    Run 'show interfaces gre' to list GRE tunnel status, or use 'show interfaces statistics' to check for GRE traffic counters
    Affected if There is active GRE traffic being processed by the device, as the vulnerability requires sending GRE packets with more than 512B of data at a high rate to trigger the ASIC error

A user is affected if they are running a vulnerable Junos OS version on an MX Series device with GRE tunnels carrying traffic, as the DoS requires both the vulnerable version and GRE packet processing to be exploited.

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

Upgrade Junos OS on MX Series devices to the fixed versions: 21.2R3-S9, 21.4R3-S8, 22.2R3-S4, 22.4R3-S5, 23.2R2-S2, or 23.4R2 or later. If immediate patching is not possible, consider filtering or rate-limiting GRE traffic destined to the device as a temporary mitigation.

Recommended fix High confidence

Minimum fixed release based on your current branch: 21.2R3-S9, 21.4R3-S8, 22.2R3-S4, 22.4R3-S5, 23.2R2-S2, or 23.4R2 (whichever is applicable)

  1. 1. Identify the currently installed Junos OS version on the MX Series device using 'show version'
  2. 2. Based on your current version branch, upgrade to the minimum fixed release:
  3. - If on 21.2 branch: upgrade to 21.2R3-S9 or later
  4. - If on 21.4 branch: upgrade to 21.4R3-S8 or later
  5. - If on 22.2 branch: upgrade to 22.2R3-S4 or later
  6. - If on 22.4 branch: upgrade to 22.4R3-S5 or later
  7. - If on 23.2 branch: upgrade to 23.2R2-S2 or later
  8. - If on 23.4 branch: upgrade to 23.4R2 or later
Caveat Standard Junos OS upgrade risks apply - test in a lab environment first; some hardware features may behave differently across major versions

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2025-30660 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

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
  • No spam, self-promotion, credentials, or personal data