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JunosOperating system · Juniper

CVE-2021-0282

HIGH · 7.5 CVSS v3.1 Published 2021-07-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
On Juniper Networks Junos OS devices with Multipath or add-path feature enabled, processing a specific BGP UPDATE can lead to a routing process daemon (RPD) crash and restart, causing a Denial of Service (DoS). Continued receipt and processing of this UPDATE message will create a sustained Denial of Service (DoS) condition. This BGP UPDATE message can propagate to other BGP peers with vulnerable Junos versions on which Multipath or add-path feature is enabled, and cause RPD to crash and restart. This issue affects both IBGP and EBGP deployments in IPv4 or IPv6 network. Junos OS devices that do not have the BGP Multipath or add-path feature enabled are not affected by this issue. This issue affects: Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S18; 15.1 versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S6, 18.4R3-S6; 19.1 versions prior to 19.1R3-S3;

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 specially crafted BGP UPDATE message processed on Juniper Junos OS devices with BGP Multipath or add-path feature enabled triggers a routing process daemon (RPD) crash and restart, causing denial of service. The malicious UPDATE can propagate to other vulnerable BGP peers, creating a sustained DoS condition affecting both IBGP and EBGP deployments.

MitigationDisable BGP Multipath or add-path features if not required, or apply vendor-supplied patches for affected versions; implement BGP route validation/filtering as additional defense-in-depth.

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:= 12.3= 15.1= 17.3= 17.4= 18.1= 18.2= 18.3= 18.4= 19.1

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 runs Juniper Junos OS
    Run 'show version' command to identify the operating system
    Affected if Device is not running Juniper Junos OS - not affected by this CVE
  2. Check Junos version against affected releases
    Run 'show version' and note the exact Junos version (e.g., 18.4R1, 19.1R3)
    Affected if Version equals 12.3, 15.1, 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, or 19.1 - falls within affected range
  3. Check if BGP Multipath is enabled
    Run 'show configuration protocols bgp | display set' and look for 'multipath' or 'multipath relax' configuration statements under BGP hierarchy
    Affected if BGP Multipath is configured - required condition for exploitation
  4. Check if BGP add-path is enabled
    Run 'show configuration protocols bgp group <name> | display set' or 'show configuration protocols bgp | display set' and look for 'add-path' statements
    Affected if BGP add-path feature is configured - required condition for exploitation

Device is affected only if running an affected Junos version (12.3, 15.1, 17.3-17.4, 18.1-18.4, or 19.1) AND has either BGP Multipath or add-path feature enabled in the BGP configuration.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable BGP Multipath or add-path features if not required, or apply vendor-supplied patches for affected versions; implement BGP route validation/filtering as additional defense-in-depth.

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2021-0282 in production — separate from our analysis above.

No notes yet

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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