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CVE-2025-39881 is a use-after-free vulnerability in the Linux kernel kernfs polling path used by Pressure Stall Information (PSI) cgroup monitoring. A race occurs when an open PSI pressure-monitoring file remains registered with epoll while cgroup pressure monitoring is disabled, causing the associated kernfs open-file private data to be released. If monitoring is subsequently re-enabled and epoll polls the retained file reference, the polling path can reach psi_trigger_poll() and dereference the freed private data. The upstream fix introduces kernfs_get_active_of() to acquire an active reference specifically for a kernfs open file; it fails safely if that open file has been released, preventing polling operations on released descriptors.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
23 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel use-after-free vulnerability in kernfs polling when an open file is released.
Linux kernel kernfs use-after-free vulnerability during polling when an open file is released.
Use-after-free vulnerability in Linux kernel kernfs polling when an open file is released.
A Linux kernel kernfs use-after-free vulnerability involving polling after an open file is released.
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.