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CVE-2026-98975— xfs: stop exchanging reflink flags when exchanging mappings

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： xfs：在交换映射时停止交换 reflink 标志 当交换操作覆盖两个文件从偏移量 0 到 的范围时， 函数假设所有映射均已移动，并将 reflink 标志移交给另一个文件。 这一假设是错误的。文件在 之后仍可能拥有共享块，例如在 操作将文件大小设置为更小值但未解除任何映射后。此时，reflink 标志会被清除，导致后续对该块的写入操作直接在原地进行，而非采用写时复制（CoW）机制，从而破坏共享该块的其他文件。 提交 （"xfs: fix exchange-range

CVSS 7.8 · High EPSS 0.21% · P11

Possible ATT&CK Techniques 1 AI

T1562.005

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux f0bc4d134b46607967bda1205ce3226a1bd95f42< 1fa2f3a7ef7ee0f2503a4b0afe24bc8c9d0820be affected
f0bc4d134b46607967bda1205ce3226a1bd95f42< 7d3b9b2c9dc57f93f36c716ab752548cb4db9900 affected
f0bc4d134b46607967bda1205ce3226a1bd95f42< 4756c94260e69ce42612b8220c3614f02f7a11d5 affected
f0bc4d134b46607967bda1205ce3226a1bd95f42< d84d6c1a7f1e2de9e601703a326a4c1b7b421943 affected
4.9 affected
< 4.9 unaffected
6.12.114≤ 6.12.* unaffected
6.18.57≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-98975

Vulnerability Information
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Vulnerability Title
xfs: stop exchanging reflink flags when exchanging mappings
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: xfs: stop exchanging reflink flags when exchanging mappings When an exchange covers both files from offset 0 to i_disk_size, xmi_can_exchange_reflink_flags() assumes every mapping moved and hands the reflink flag over to the other file. That assumption is wrong. A file can still own shared blocks past i_disk_size, e.g. after EXCHANGE_RANGE_TO_EOF sets a smaller size without unmapping anything. The flag is cleared anyway, and the next write to such a block happens in place instead of CoW, corrupting the other file that shares it. Commit a23eca88448e ("xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN") fixed one instance of this. Rather than add another special case, stop moving the flags. xfs_exchmaps_ensure_reflink() already sets the flag on both inodes before the exchange, so both just keep it. Nothing sets CLEAR_INO{1,2}_REFLINK anymore. Intents logged by older kernels may still carry them; recovery already masks them off, so they stay in the log format mask and are ignored. XFS_IOC_SWAPEXT has the same problem: it moves the reflink flag from one inode to the other along with the extents. Just removing that is not enough here: the exchange path flags both inodes up front in xfs_exchmaps_ensure_reflink(), but swapext has no such step, so the inode receiving the shared extents would be left without the flag. Set it on both inodes instead, and make sure both have a CoW fork, since an inode with the reflink flag is expected to have one. The flag now stays until FALLOC_FL_UNSHARE_RANGE, xfs_scrub, or a truncate to zero removes it.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux f0bc4d134b46607967bda1205ce3226a1bd95f42 ~ 1fa2f3a7ef7ee0f2503a4b0afe24bc8c9d0820be -
Linux Linux 4.9 -

II. Public POCs for CVE-2026-98975

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III. Intelligence Information for CVE-2026-98975

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Patches & Fixes for CVE-2026-98975 (3)

Same Patch Batch · Linux · 2026-10-23 · 218 CVEs total

CVE-2026-98959 9.8 CRITICAL btrfs: fix xattr replace when multiple xattrs are packed in the same item
CVE-2026-99079 9.8 CRITICAL net/mlx5e: Prevent stale XSK buffer release on refill retry
CVE-2026-99078 9.8 CRITICAL net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
CVE-2026-98870 8.8 HIGH ksmbd: remove stale channels from all sessions on teardown
CVE-2026-98988 8.8 HIGH namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE
CVE-2026-99083 8.8 HIGH ksmbd: fix heap out-of-bounds write in krb5_authenticate()
CVE-2026-99082 8.8 HIGH KVM: x86: Use active memslots for the per-vCPU MMIO cache
CVE-2026-98981 8.8 HIGH namespace: unhash a dentry before detaching the mounts on it
CVE-2026-98980 8.8 HIGH namei: don't reveal overmounted entries in refwalk
CVE-2026-99042 8.4 HIGH io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6
CVE-2026-98978 8.4 HIGH namespace: never expire a locked mount
CVE-2026-99064 8.1 HIGH cipso: adjust cached option offsets when removing CIPSO
CVE-2026-98968 8.1 HIGH amt: send the relay's General Query directly from the receive path
CVE-2026-98889 7.8 HIGH wifi: iwlwifi: mvm: fix sched scan IE sizing
CVE-2026-98991 7.8 HIGH namespace: queue a mount only once for mount notifications
CVE-2026-98944 7.8 HIGH HID: steam: Refactor registration
CVE-2026-99056 7.8 HIGH strparser: make sure __strp_recv isn't running before tearing down the parser
CVE-2026-98999 7.8 HIGH drm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin
CVE-2026-99054 7.8 HIGH tipc: destroy topsrv workqueues before closing connections
CVE-2026-99032 7.8 HIGH net/smc: protect clcsock lifetime in smc_getname

Showing top 20 of 218 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98975

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