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CVE-2021-20226 is a use-after-free vulnerability in the Linux kernel io_uring subsystem caused by incorrect reference counting of file-related objects during asynchronous work handling. The flaw stems from io_uring worker processing retaining a pointer to the calling task's files_struct without properly incrementing its reference count, allowing the object lifetime to end while it is still referenced by deferred work. In affected conditions, subsequent file-descriptor handling can interact with fdget() behavior that may avoid incrementing a struct file reference when files_struct->count remains 1, creating a path where a file object can be freed by a concurrent close while still in use. This results in a kernel use-after-free condition in file-related operations and can be leveraged by a local attacker to escalate privileges to root. The vulnerability affects confidentiality, integrity, and availability.
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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.
A previously found vulnerability in the Linux kernel io_uring subsystem, mentioned as an example of bugs discovered in that codebase.
A Linux kernel io_uring reference counting bug that can lead to local privilege escalation to root via use-after-free conditions involving files_struct/file handling in asynchronous worker context.
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.