Bug 2507098 (CVE-2026-64266)

Summary: CVE-2026-64266 kernel: fuse: re-lock request before returning from fuse_ref_folio()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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 (Filesystem in Userspace) component. The `fuse_ref_folio()` function does not properly re-lock a request after unlocking it, which can lead to a use-after-free vulnerability. A local attacker could exploit this flaw to potentially execute arbitrary code or cause a denial of service.
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Description OSIDB Bzimport 2026-07-25 10:04:53 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fuse: re-lock request before returning from fuse_ref_folio()

fuse_ref_folio() unlocks the request but does not re-lock it before
returning. fuse_chan_abort() can end the request and the async end
callback (eg fuse_writepage_free()) can free the args while the
subsequent copy chain logic after fuse_ref_folio() accesses them,
leading to use-after-free issues.

Fix this by locking the request in fuse_ref_folio() before returning.
Comment 1 TEJ RATHI 2026-07-30 06:36:19 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072558-CVE-2026-64266-67e6@gregkh/T