CVE-2020-1651
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 · uneditedOn Juniper Networks MX series, receipt of a stream of specific Layer 2 frames may cause a memory leak resulting in the packet forwarding engine (PFE) on the line card to crash and restart, causing traffic interruption. By continuously sending this stream of specific layer 2 frame, an attacker connected to the same broadcast domain can repeatedly crash the PFE, causing a prolonged Denial of Service (DoS). This issue affects Juniper Networks Junos OS on MX Series: 17.2 versions prior to 17.2R3-S4; 17.2X75 versions prior to 17.2X75-D105.19; 17.3 versions prior to 17.3R3-S7; 17.4 versions prior to 17.4R1-S3, 17.4R2; 18.1 versions prior to 18.1R2. This issue does not affect Juniper Networks Junos OS releases prior to 17.2R1.
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 confidenceA memory leak vulnerability in Juniper Networks MX series routers allows an attacker on the same broadcast domain to send specific Layer 2 frames that exhaust memory on the Packet Forwarding Engine (PFE), causing it to crash and restart. Repeated exploitation results in prolonged denial of service.
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= 17.2= 17.2x75= 17.3= 17.4= 18.1CVSS 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 checksWork through these to decide whether this CVE applies to you.
-
Identify the Junos OS versionRun 'show version' via CLI or check the system version bannerAffected if The version matches = 17.2, = 17.2x75, = 17.3, = 17.4, or = 18.1 exactly
-
Confirm the device is an MX series routerRun 'show chassis hardware' or 'show system information' and verify the model is MX-seriesAffected if The hardware model is an MX-series router (MX5, MX10, MX40, MX80, MX104, MX240, MX480, MX960, etc.)
-
Verify if Layer 2 bridging or IRB interfaces are configuredRun 'show interfaces irb' or 'show bridge domain' to see if Layer 2 interfaces existAffected if IRB interfaces or bridge domains are configured and active, allowing Layer 2 frame processing
-
Check if the PFE is experiencing memory exhaustionRun 'show pfe traffic' or 'show pfe errors' to inspect PFE memory and error statisticsAffected if PFE shows high memory utilization, frequent restarts, or error counters indicating memory exhaustion
A user is affected if they are running an MX-series router with Junos version 17.2, 17.2x75, 17.3, 17.4, or 18.1 and have Layer 2 services (IRB/bridging) enabled on the same broadcast network where an attacker can send malicious frames.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataApply the vendor-supplied patches for affected Junos OS versions (17.2R3-S4 and later, 17.2X75-D105.19 and later, 17.3R3-S7 and later, 17.4R1-S3/17.4R2 and later, 18.1R2 and later). Consider network segmentation to limit attack surface.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-1651 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-1651 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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