Security readout for executives and security teams
Plain-English summary
CVE-2020-3338 is a denial-of-service flaw in Cisco NX-OS handling of IPv6 PIM multicast traffic. Crafted PIM6 packets can make the PIM6 application leak memory until legitimate PIM6 traffic is no longer processed.
Executive priority
Treat as high priority for networks relying on IPv6 multicast or Cisco NX-OS devices in core switching roles. The business risk is service disruption, not data theft.
Technical view
The vulnerability is improper error handling in the PIM6 feature of Cisco NX-OS Software. An unauthenticated remote attacker can send multiple crafted inbound PIM6 packets, causing a system memory leak in the PIM6 application and eventual availability impact.
Likely exposure
Exposure is most likely where Cisco NX-OS Software 5.2(1) devices process IPv6 PIM multicast traffic. Risk depends on whether PIM6 is enabled and reachable from untrusted or poorly controlled network segments.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires sending crafted PIM6 packets to an affected device, with impact accumulating over time through memory leakage.
Researcher notes
The bundle identifies CWE-404 and CVSS 7.5 with network, low-complexity, no-authentication attack conditions. It does not provide exploit confirmation, detailed affected platform matrix, or named remediation details beyond the Cisco advisory reference.
Mitigation direction
- Review Cisco advisory for fixed software and official workarounds.
- Inventory NX-OS devices and confirm whether version 5.2(1) is present.
- Identify devices with PIM6 enabled or receiving IPv6 multicast control traffic.
- Limit PIM6 exposure to trusted network paths where operationally feasible.
- Monitor affected devices for PIM6 memory growth or application failure.
Validation and detection
- Check device software versions against Cisco's advisory.
- Confirm whether IPv6 PIM multicast is enabled on each NX-OS device.
- Review network paths that can deliver inbound PIM6 packets to affected devices.
- Look for logs or telemetry showing PIM6 memory leakage or service degradation.
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-404: 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-2020-3338 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 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/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:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.5HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200826 Cisco NX-OS Software IPv6 Protocol Independent Multicast Denial of Service VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
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.
Improper Resource Shutdown or Release
Improper Resource Shutdown or Release represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.