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CVE-2021-4206 is an integer-overflow vulnerability in QEMU's QXL paravirtualized display-device cursor handling. Guest-controlled cursor width and height are multiplied in cursor_alloc() using an int-sized calculation. Values such as 0x8000 for both dimensions can overflow the calculated cursor-data size to zero, resulting in an undersized allocation. Subsequent chunk unpacking recalculates the expected size and copies guest-controlled cursor data with memcpy(), producing a heap-based buffer overflow in the QEMU process.
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What an attacker gets, and what they’ve been doing with it.
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Patch, then assume compromise.
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No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An integer-overflow vulnerability in QEMU's QXL cursor allocation path that can lead to a heap buffer overflow.
An integer overflow leading to heap overflow in the QEMU QXL video accelerator's cursor handling logic, affecting guest-to-host interaction through the QXL device.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.