CVE-2026-89543
Low risk· EPSS 11%Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
A use-after-free vulnerability exists in the Linux kernel in __rpc_clnt_handle_event and __rpc_clnt_remove_pipedir within the sunrpc subsystem. The clnt->pipefs_sb field is not refreshed on mount events nor cleared on unmount, causing comparison against a stale pointer and skipped cleanup. As a result, pipefs dentries may point to a freed rpc_clnt, leading to use-after-free during subsequent rpc_info_open() or rpc_show_info() calls.
Risk Assessment
Can lead to kernel memory corruption, system crash (panic), or potential privilege escalation by a local attacker. Affects systems using NFS/SUNRPC with pipefs.
Recommendation
Update the Linux kernel to a version containing the fix that properly updates clnt->pipefs_sb on mount events and clears it during unmount or failure paths.
Other vulnerabilities in Linux kernel
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- CVE-2026-99258Unknown
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- CVE-2026-99257Unknown
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- CVE-2026-99256Unknown
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- CVE-2026-99251Unknown
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- CVE-2026-99250Unknown
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- CVE-2026-99249Unknown
In the Linux kernel, zap_pid_ns_processes() waiting for PID namespace cleanup was not freezable. A tracer outside the namespace that does not reap its traced zombies keeps PIDs allocated, making the wait unbounded and causing every suspend attempt to fail. The fix makes the wait loops use TASK_FREEZABLE states so the freezer can freeze waiting tasks.
- CVE-2026-99248Unknown
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- CVE-2026-99247Unknown
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: sunrpc: fix use-after-free in __rpc_clnt_handle_event and __rpc_clnt_remove_pipedir Normal client creation goes through rpc_setup_pipedir(), which records clnt->pipefs_sb, but the mount-event path in __rpc_clnt_handle_event() calls rpc_setup_pipedir_sb() directly and never refreshes that field. The umount path also removes the directory without clearing clnt->pipefs_sb. After a late pipefs mount or any remount, rpc_clnt_remove_pipedir() compares the current superblock against a stale pipefs_sb pointer and skips cleanup, leaving pipefs dentries whose inode private data still points at a freed rpc_clnt, leading to a potential use-after-free during subsequent rpc_info_open() or rpc_show_info() calls. Fix this by properly updating clnt->pipefs_sb upon mount events and clearing it during unmount or failure paths.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

