Security readout for executives and security teams
Plain-English summary
A crafted IPv4 packet sent to certain Juniper routing and switching platforms can restart line-card hardware. When that FPC restarts, traffic through it drops; repeated packets can create a sustained outage. Risk is highest for exposed control planes on affected MX, PTX, and QFX platforms running the cited Junos 19.2-19.4 or Junos OS Evolved releases.
Executive priority
Treat this as high priority for core network infrastructure because successful exploitation can interrupt traffic forwarding. It is not described as data theft or system takeover, but outage impact can be material where affected FPCs carry production traffic.
Technical view
CVE-2020-1638 is a network unauthenticated denial-of-service issue in specific Junos OS and Junos OS Evolved releases. The packet must be IPv4 and destined to the device itself, reaching the Routing Engine despite edge and control-plane filters. IPv6 is not affected. Affected hardware includes MX with MPC10E/MPC11E, PTX10001, QFX5220, and PTX10003 series.
Likely exposure
Exposure is limited to listed Juniper platforms and software versions. Devices with reachable management, control-plane, or device-destined IPv4 paths have higher concern. Existing edge and control-plane filtering may reduce reachability, but the source does not say filtering fully mitigates the issue.
Exploitation context
The provided sources do not report active exploitation, and the CVE is not marked KEV. The vulnerability is remotely reachable with low attack complexity and no privileges, but only when the specific IPv4 traffic reaches the device itself. Repeated triggering can extend denial of service.
Researcher notes
The key exposure boundary is device-destined IPv4 reaching the Routing Engine, not transit IPv4 or IPv6 generally. Sources identify affected trains and platforms but provide limited mitigation detail beyond fixed releases and existing filtering context. Do not assume all Junos devices are affected.
Mitigation direction
- Upgrade Junos OS 19.2, 19.3, or 19.4 to the fixed releases named by Juniper.
- For Junos OS Evolved, follow Juniper advisory guidance for fixed or unaffected releases.
- Restrict device-destined IPv4 traffic through edge and control-plane filters.
- Prioritize internet-facing or provider-edge devices carrying critical traffic.
- Monitor for unexpected FPC restarts and traffic drops until remediation is complete.
Validation and detection
- Inventory affected MX, PTX, and QFX platforms and installed Junos releases.
- Confirm whether MPC10E, MPC11E, PTX10001, QFX5220, or PTX10003 hardware is present.
- Check whether IPv4 traffic can reach the device control plane from untrusted networks.
- Review logs and telemetry for FPC restarts or correlated traffic drops.
- Verify installed versions meet or exceed Juniper's named fixed releases.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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Open ATT&CK lookupCVE-2020-1638 mapping review
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Open ATT&CK lookup- 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
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.
CVSS vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.juniper.net/JSA11019CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of sizeof() on a Pointer Type
Use of sizeof() on a Pointer Type represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.