CVE-2019-20808
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn QEMU 4.1.0, an out-of-bounds read flaw was found in the ATI VGA implementation. It occurs in the ati_cursor_define() routine while handling MMIO write operations through the ati_mm_write() callback. A malicious guest could abuse this flaw to crash the QEMU process, resulting in a denial of service.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceAn out-of-bounds read vulnerability exists in QEMU 4.1.0's ATI VGA emulation within the ati_cursor_define() function. The flaw is triggered when a malicious guest performs MMIO write operations through the ati_mm_write() callback, allowing the guest to read beyond allocated buffer boundaries and crash the QEMU process.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 4.1.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed QEMU versionRun 'qemu-img --version' or check the installed package version via your system package manager (dpkg -l qemu, rpm -q qemu, etc.)Affected if The installed QEMU version is exactly 4.1.0 (note: other versions may have similar issues but this CVE specifically affects 4.1.0)
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Confirm QEMU process is running with ATI VGA emulationInspect the running QEMU process command line: check /proc/<qemu-pid>/cmdline or use 'ps aux | grep qemu' to see if the emulated VGA device is ATI-related (look for parameters like '-vga ati' or device definitions referencing ATI)Affected if QEMU is emulating an ATI VGA device for the affected guest
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Verify MMIO access is enabled for the guestCheck the QEMU command line for PCI device assignment or MMIO configuration related to the ATI VGA device. Look for -device parameters involving ati-vga or similar ATI-related device definitions with MMIO regionsAffected if The guest has PCI/MMIO access to the emulated ATI VGA device (this is required for the malicious MMIO writes to trigger the flaw)
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Confirm guest can perform MMIO writesReview the hypervisor or cloud platform configuration to determine whether the untrusted guest has direct PCI access or pass-through that allows MMIO write operations to the emulated ATI deviceAffected if The guest operating system has the ability to perform MMIO write operations to the emulated hardware
You are affected if you are running QEMU version 4.1.0 with ATI VGA emulation enabled and the guest has MMIO write access to that emulated device.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpdate QEMU to a version that includes the fix for this vulnerability. In the interim, consider restricting PCI/MMIO access from untrusted guests or implementing hypervisor-level memory isolation as compensating controls.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-20808 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2019-20808 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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