Security readout for executives and security teams
Plain-English summary
This flaw can make affected Juniper PTX and QFX10K routing or switching hardware restart forwarding components, interrupting traffic. It matters most for large-scale networks using inline-jflow, especially during routing instability or heavy traffic flow conditions.
Executive priority
Treat as high priority for backbone, peering, data-center fabric, or service-provider environments using affected Juniper platforms. Lower priority where PTX/QFX10K devices or inline-jflow are absent.
Technical view
CVE-2021-0270 is a use-after-free race condition in the Junos OS Packet Forwarding Engine microkernel architecture. On affected PTX Series and QFX10K Series devices with inline-jflow enabled, conditions can cause one or more FPCs to restart, generate core files, and disrupt traffic.
Likely exposure
Exposure appears limited to Juniper Networks Junos OS 18.1R2 and later 18.1 releases before 18.1R3-S10 on PTX Series and QFX10K Series devices with inline-jflow enabled.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation evidence. The issue is more likely during network instability, BGP or IGP reconvergence, and high numbers of active traffic flows.
Researcher notes
The source bundle supports denial-of-service impact, affected platform and version scope, and triggering conditions. It does not provide enough evidence to claim active exploitation, affected non-18.1 trains, or product families beyond PTX and QFX10K.
Mitigation direction
- Inventory PTX and QFX10K devices running affected Junos OS versions.
- Confirm whether inline-jflow is enabled on those devices.
- Prioritize upgrade planning to 18.1R3-S10 or later vendor-fixed guidance.
- Review Juniper advisory JSA11161 before making operational changes.
- Increase monitoring for FPC restarts, core files, and traffic disruption.
Validation and detection
- Check Junos OS version against the affected 18.1 range.
- Verify device family is PTX Series or QFX10K Series.
- Confirm inline-jflow configuration status.
- Review logs for unexpected FPC restarts and generated core files.
- Correlate incidents with reconvergence events or unusually large traffic-flow periods.
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
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.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-362: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-0270 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
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/JSA11161CVE reference · x_refsource_MISC
- https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/inline-flow-monitoring-ptx.htmlCVE reference · x_refsource_MISC
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.
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.