Bug 2502255 (CVE-2026-53388)

Summary: CVE-2026-53388 kernel: fuse: re-lock request before replacing page cache folio
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerability-draftAssignee: 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
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's Filesystem in Userspace (FUSE) component. The `fuse_try_move_folio()` function, responsible for managing page cache folios, fails to re-lock a request after initially unlocking it on a successful path. This oversight allows another function, `fuse_chan_abort()`, to prematurely free critical input/output arguments (`fuse_io_args`). Consequently, subsequent operations attempting to access these freed arguments can lead to a use-after-free vulnerability, potentially allowing an attacker to cause a system crash or execute arbitrary code.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-07-19 13:04:19 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fuse: re-lock request before replacing page cache folio

fuse_try_move_folio() unlocks the request on entry but does not
re-lock it on the success path. This means fuse_chan_abort() can end the
request and free the fuse_io_args (eg fuse_readpages_end()) while the
subsequent copy chain logic after fuse_try_move_folio() accesses the
fuse_io_args, leading to use-after-free issues.

Fix this by calling lock_request() before replace_page_cache_folio().
This ensures the request is locked on the success path which will
prevent the fuse_io_args from being freed while the later copying logic
runs, and also ensures that the ap->folios[i]->mapping is never null
since ap->folios[i] will always point to the newfolio after
replace_page_cache_folio().
Comment 1 Keith Grant 2026-07-20 13:42:08 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071935-CVE-2026-53388-eeaf@gregkh/T