Bug 2507041 (CVE-2026-64265)

Summary: CVE-2026-64265 kernel: fuse: clear intr_entry in fuse_resend and fuse_remove_pending_req
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's fuse component. When a fuse request is interrupted and then resent, a specific interrupt entry (`intr_entry`) is not properly cleared. If the requesting task subsequently receives a fatal signal, this uncleared entry can lead to a use-after-free condition. This vulnerability can result in memory corruption, potentially causing a system crash, and may also lead to the disclosure of sensitive data to userspace.
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Description OSIDB Bzimport 2026-07-25 10:01:55 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fuse: clear intr_entry in fuse_resend and fuse_remove_pending_req

When fuse_resend() moves a request from fpq->processing back to
fiq->pending, it sets FR_PENDING and clears FR_SENT but does not
remove the requests intr_entry from fiq->interrupts.  If the
request had FR_INTERRUPTED set from a prior signal, intr_entry
remains dangling on fiq->interrupts.  When the requesting task
then receives a fatal signal, fuse_remove_pending_req() sees
FR_PENDING=1, removes the request from fiq->pending and frees it
via the refcount path, also without cleaning intr_entry.  The
stale intr_entry causes use-after-free when fuse_read_interrupt()
iterates fiq->interrupts:
  - list_del_init(&req->intr_entry) -> UAF write on freed slab
  - req->in.h.unique -> UAF read, data leaked to userspace

Remove intr_entry from fiq->interrupts in fuse_resend() for
interrupted requests before they are placed back on fiq->pending.

Add a WARN_ON if the intr_entry is not empty on request destruction.
Comment 1 Mauro Matteo Cascella 2026-07-28 16:34:57 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072558-CVE-2026-64265-5f6c@gregkh/T