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CVE Record

CVE-2020-1626: Junos OS Evolved: Denial of Service vulnerability in processing high rate of specific packets

A vulnerability in Juniper Networks Junos OS Evolved may allow an attacker to cause a Denial of Service (DoS) by sending a high rate of specific packets to the device, resulting in a pfemand process crash. The pfemand process is responsible for packet forwarding on the device. By continuously sending the packet flood, an attacker can repeatedly crash the pfemand process causing a sustained Denial of Service. This issue can only be triggered by traffic sent to the device. Transit traffic does not cause this issue. This issue affects all version of Junos OS Evolved prior to 19.1R1-EVO.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw can let an unauthenticated network attacker disrupt affected Juniper Junos OS Evolved devices by overwhelming traffic directed at the device itself. The crash affects pfemand, the packet-forwarding process, and repeated flooding can sustain an outage. Transit traffic through the device is not reported to trigger the issue.

Executive priority

Treat as high priority for exposed Juniper infrastructure because the impact is availability loss on network devices. Prioritize internet-facing, partner-facing, or otherwise untrusted-reachable devices first, then complete version validation across the fleet.

Technical view

CVE-2020-1626 affects Juniper Networks Junos OS Evolved before 19.1R1-EVO. A high rate of specific packets sent to the device can crash pfemand, causing denial of service. CVSS 3.1 is 7.5, network exploitable, low complexity, no privileges, no user interaction, availability impact only.

Likely exposure

Exposure is most likely where Junos OS Evolved devices before 19.1R1-EVO can receive untrusted traffic addressed to the device. Devices only forwarding transit traffic are less directly exposed based on the provided source description.

Exploitation context

The provided sources do not report active exploitation, and this CVE is not marked KEV. The weakness is still operationally important because a repeatable process crash in packet forwarding can create sustained device-level denial of service.

Researcher notes

Key constraints matter: the trigger is traffic sent to the device, not transit traffic. The source bundle identifies Junos OS Evolved before 19.1R1-EVO, but does not provide exploit details or confirm exploitation in the wild.

Mitigation direction

  • Identify Junos OS Evolved devices and compare versions against 19.1R1-EVO.
  • Upgrade affected systems to a non-affected release per Juniper guidance.
  • Restrict untrusted traffic addressed directly to network devices.
  • Review router control-plane protection guidance referenced by RFC6192.
  • Monitor Juniper advisory JSA11005 for exact remediation guidance.

Validation and detection

  • Inventory Junos OS Evolved versions across routing and switching assets.
  • Confirm whether any device runs a release prior to 19.1R1-EVO.
  • Check which interfaces can receive traffic addressed to the device.
  • Review logs for pfemand crashes or repeated forwarding-process restarts.
  • Verify control-plane filters limit untrusted device-destined traffic.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2020-1626 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2020-1626Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Juniper NetworksJunos OS EvolvedunspecifiedListed
Weakness

CWE details

No CWE listed

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