Security readout for executives and security teams
Plain-English summary
A flaw in Moby HyperKit can let a guest workload crash the host, and in some circumstances corrupt memory. This is a high-priority infrastructure risk where HyperKit is used to run virtualized workloads, especially if guest workloads are untrusted or externally supplied.
Executive priority
Treat this as a high-priority remediation for affected virtualization hosts. The main business risk is host outage from a guest-triggered crash, with possible memory corruption under some conditions. There is no provided evidence of active exploitation.
Technical view
In HyperKit 0.20210107 and earlier, pci_vtrnd_notify does not check vq_getchain failure. That can leave struct iovec uninitialized before read() uses its base and length fields. The reported impact is host denial of service and possible memory corruption. The issue is fixed by commit 41272a980197917df8e58ff90642d14dec8fe948.
Likely exposure
Exposure is limited to environments running Moby HyperKit 0.20210107 or earlier, including embedded uses of HyperKit. The sources do not identify broader product packaging, so teams should verify direct and vendored HyperKit usage rather than assume a named downstream product is affected.
Exploitation context
The CVSS vector is local, low complexity, no privileges, and no user interaction. The provided sources do not report active exploitation, and the CVE is not marked KEV. Risk rises where untrusted guests can interact with HyperKit-backed virtual devices.
Researcher notes
The root cause is CWE-908: use of uninitialized resource. The vulnerable path is qnotify at pci_vtrnd_notify, where vq_getchain failure leaves iov uninitialized before read(sc->vrsc_fd, iov.iov_base, iov.iov_len). Keep validation focused on version lineage and fix inclusion.
Mitigation direction
- Inventory direct and vendored Moby HyperKit deployments.
- Upgrade to a HyperKit build containing commit 41272a980197917df8e58ff90642d14dec8fe948.
- If no packaged fix is available, follow current Moby HyperKit vendor guidance.
- Avoid running untrusted guest workloads on affected HyperKit hosts.
- Prioritize hosts supporting shared development or multi-user virtualization workflows.
Validation and detection
- Check installed or embedded HyperKit version information.
- Confirm the fix commit is present in the deployed source or package.
- Review software bills of materials for vendored HyperKit copies.
- Verify vulnerable hosts are not running untrusted guest workloads.
- Track remediation status against all systems using HyperKit 0.20210107 or earlier.
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-908: 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-2021-32845 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
- 7.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/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:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H2.55.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.7HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Source materials
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 Uninitialized Resource
Use of Uninitialized Resource represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.