Security readout for executives and security teams
Plain-English summary
CVE-2020-17391 affects Parallels Desktop 15.1.3-47255 on macOS. A local low-privileged attacker could use an exposed hypervisor kernel extension interface to disclose sensitive information. The main business risk is not remote takeover by itself, but use as part of a chain toward kernel-level compromise.
Executive priority
Treat as a targeted endpoint hardening issue, not an internet-wide emergency. Prioritize developer and privileged-user Macs first because successful chaining could affect kernel security boundaries and sensitive local data.
Technical view
The flaw is in the prl_hypervisor kernel extension handler for HOST_IOCTL_INIT_HYPERVISOR. ZDI describes dangerous functionality exposed to unprivileged users, enabling local information disclosure. CVSS is 6.5 with local attack vector, low complexity, low privileges required, no user interaction, changed scope, and high confidentiality impact.
Likely exposure
Exposure is limited to macOS systems running Parallels Desktop 15.1.3-47255, especially developer, engineering, QA, or admin workstations where local users or malware can execute code.
Exploitation context
The provided sources require prior low-privileged local code execution. The CVE is not listed as CISA KEV in the bundle, and no cited source here establishes active exploitation. ZDI notes it could be chained with other vulnerabilities for kernel-context code execution.
Researcher notes
Evidence supports local information disclosure through an exposed hypervisor kext method. The bundle does not provide exploit details, a fixed version, or proof of in-the-wild exploitation. Validate exposure by product version and kernel extension presence, then follow vendor guidance.
Mitigation direction
- Inventory macOS endpoints for Parallels Desktop 15.1.3-47255.
- Review Parallels KB 125013 for vendor-confirmed fixed builds or guidance.
- Upgrade affected installations according to Parallels guidance.
- Remove or disable Parallels Desktop where it is not business-required.
- Restrict untrusted local access on affected macOS systems.
Validation and detection
- Confirm whether Parallels Desktop 15.1.3-47255 is installed on any macOS host.
- Verify affected hosts are upgraded or removed after remediation.
- Check whether prl_hypervisor kext is present on systems marked remediated.
- Review endpoint telemetry for suspicious local privilege escalation activity.
- Document exceptions where Parallels remains installed but not yet updated.
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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-17391 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
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:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N24Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.5MediumVector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.parallels.com/en/125013CVE reference · x_refsource_MISC
- https://www.zerodayinitiative.com/advisories/ZDI-20-1009/CVE 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.
Exposed Dangerous Method or Function
Exposed Dangerous Method or Function represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.