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JunosOperating system · Juniper

CVE-2021-0250

HIGH · 7.5 CVSS v3.1 Published 2021-04-22
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
In segment routing traffic engineering (SRTE) environments where the BGP Monitoring Protocol (BMP) feature is enable, a vulnerability in the Routing Protocol Daemon (RPD) process of Juniper Networks Junos OS allows an attacker to send a specific crafted BGP update message causing the RPD service to core, creating a Denial of Service (DoS) Condition. Continued receipt and processing of this update message will create a sustained Denial of Service (DoS) condition. This issue affects IPv4 and IPv6 environments. This issue affects: Juniper Networks Junos OS 17.4 versions 17.4R1 and above prior to 17.4R2-S6, 17.4R3; 18.1 versions prior to 18.1R3-S7; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3; 19.1 versions prior to 19.1R1-S4, 19.1R2; 19.2 versions prior to 19.2R1-S3, 19.2R2, This issue does not affect Junos OS releases prior to 17.4R1. This issue affects: Juniper Networks Junos OS Evolved 19.2-EVO versions prior to 19.2R2-EVO.

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

In Junos OS with BMP (BGP Monitoring Protocol) enabled in SRTE (Segment Routing Traffic Engineering) environments, a specifically crafted BGP update message sent to the Routing Protocol Daemon (RPD) causes the RPD process to crash (core dump), resulting in a Denial of Service. Continued receipt of such messages sustains the DoS condition.

MitigationUpgrade to the fixed Junos OS versions (17.4R2-S6, 17.4R3, 18.1R3-S7, 18.2R2-S6, 18.2R3-S3, 18.3R1-S7, 18.3R2-S3, 18.3R3, 18.4R1-S5, 18.4R2-S3, 18.4R3, 19.1R1-S4, 19.1R2, 19.2R1-S3, 19.2R2, or 19.2R2-EVO as applicable). As a workaround, disable BMP in SRTE environments or implement BGP peering filters to block untrusted BGP updates.

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:= 17.4= 18.1= 18.2= 18.3= 18.4= 19.1= 19.2
Junos Os EvolvedOperating system
Affected:= 19.2

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
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. Check Junos OS version
    Run 'show version' or 'system show version' command to obtain the installed Junos OS version
    Affected if The installed version is 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, or 19.2 (any version in these branches) on Junos OS, or version 19.2 on Junos OS Evolved
  2. Verify BMP is enabled
    Run 'show configuration protocols bmp' or check for BMP-related configuration under the [protocols bmp] hierarchy
    Affected if BMP is actively configured and enabled in the device configuration
  3. Confirm SRTE configuration exists
    Run 'show configuration routing-options source-packet-routing' or check for SRTE-related configuration under [routing-options source-packet-routing]
    Affected if Segment Routing Traffic Engineering (SRTE) is configured on the device
  4. Verify RPD crash activity
    Check for RPD core dumps in /var/crash/ or run 'show system core-dumps' to review recent RPD process crashes
    Affected if RPD process has recently crashed or generated core dumps, and conditions above are met

The device is affected if it runs a vulnerable Junos version (17.4-19.2 for Junos OS or 19.2 for Junos OS Evolved) AND has BMP enabled AND has SRTE configured, making it susceptible to RPD crashes from crafted BGP updates.

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

Upgrade to the fixed Junos OS versions (17.4R2-S6, 17.4R3, 18.1R3-S7, 18.2R2-S6, 18.2R3-S3, 18.3R1-S7, 18.3R2-S3, 18.3R3, 18.4R1-S5, 18.4R2-S3, 18.4R3, 19.1R1-S4, 19.1R2, 19.2R1-S3, 19.2R2, or 19.2R2-EVO as applicable). As a workaround, disable BMP in SRTE environments or implement BGP peering filters to block untrusted BGP updates.

Fix this in Junos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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-2021-0250 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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