Security readout for executives and security teams
Plain-English summary
CVE-2021-31370 can let a nearby network attacker disrupt Juniper QFX5000 and EX4600 switches by sending high-rate specific multicast traffic. The impact is denial of service: control traffic, including routing protocols, may be dropped while the traffic continues.
Executive priority
Treat as a moderate infrastructure availability risk. It is not a data-theft issue, but disruption to switching control protocols can affect network stability. Prioritize remediation for core, aggregation, and shared tenant networks.
Technical view
The issue is CWE-184 in the Packet Forwarding Engine input handling of Junos OS on QFX5000 and EX4600 Series. It is adjacent-network, unauthenticated, low-complexity, and affects availability only. Vulnerable release trains include pre-fixed versions from 17.3 through 21.1 as listed by Juniper.
Likely exposure
Exposure is mainly internal or adjacent Layer 2/nearby network environments where an attacker can send the relevant multicast traffic to affected switches. Internet-wide remote exposure is not supported by the provided sources.
Exploitation context
The source bundle does not show CISA KEV listing or confirmed active exploitation. Exploitation requires adjacent network access and sustained high-rate specific multicast traffic to maintain denial of service.
Researcher notes
Key constraints are adjacent attacker position and affected PFE behavior under high-rate specific multicast traffic. The public sources identify affected trains and fixed release thresholds, but do not provide public exploitation evidence in this bundle.
Mitigation direction
- Inventory QFX5000 and EX4600 devices and record their Junos OS versions.
- Upgrade affected devices to Juniper fixed releases or later supported releases.
- Prioritize switches carrying critical routing or aggregation control traffic.
- Check Juniper JSA11232 for platform-specific guidance before deferring upgrade.
Validation and detection
- Confirm whether deployed hardware is QFX5000 Series or EX4600 Series.
- Compare installed Junos OS versions against Juniper's affected version ranges.
- Review monitoring for routing or control-plane instability during multicast spikes.
- After remediation, verify the release is at or above the fixed threshold.
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-184: 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-2021-31370 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
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/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:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:A/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/JSA11232CVE 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.
Incomplete List of Disallowed Inputs
Incomplete List of Disallowed Inputs represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.