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CVE-2025-39899— mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE

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.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于kmap_local未遵循后进先出顺序，可能导致空指针取消引用。

AI Predicted 5.5 Difficulty: Theoretical EPSS 0.15% · P4

Possible ATT&CK Techniques 1 AI

T1055 · Process Injection

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux adef440691bab824e39c1b17382322d195e1fab0< b051f707018967ea8f697d790a1ed8c443f63812 affected
adef440691bab824e39c1b17382322d195e1fab0< bd1ee62759d0bd4d6b909731c076c230ac89d61e affected
adef440691bab824e39c1b17382322d195e1fab0< 9614d8bee66387501f48718fa306e17f2aa3f2f3 affected
6.8 affected
< 6.8 unaffected
6.12.46≤ 6.12.* unaffected
6.16.6≤ 6.16.* unaffected
6.17≤ * unaffected
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I. Basic Information for CVE-2025-39899

Vulnerability Information
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Vulnerability Title
mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE With CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using kmap_local_page(), which requires unmapping in Last-In-First-Out order. The current code maps dst_pte first, then src_pte, but unmaps them in the same order (dst_pte, src_pte), violating the LIFO requirement. This causes the warning in kunmap_local_indexed(): WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c addr \!= __fix_to_virt(FIX_KMAP_BEGIN + idx) Fix this by reversing the unmap order to respect LIFO ordering. This issue follows the same pattern as similar fixes: - commit eca6828403b8 ("crypto: skcipher - fix mismatch between mapping and unmapping order") - commit 8cf57c6df818 ("nilfs2: eliminate staggered calls to kunmap in nilfs_rename") Both of which addressed the same fundamental requirement that kmap_local operations must follow LIFO ordering.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于kmap_local未遵循后进先出顺序，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux adef440691bab824e39c1b17382322d195e1fab0 ~ b051f707018967ea8f697d790a1ed8c443f63812 -
Linux Linux 6.8 -

II. Public POCs for CVE-2025-39899

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III. Intelligence Information for CVE-2025-39899

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Patches & Fixes for CVE-2025-39899 (1)

Same Patch Batch · Linux · 2025-10-01 · 169 CVEs total

CVE-2023-53517 9.8 CRITICAL tipc: do not update mtu if msg_max is too small in mtu negotiation
CVE-2025-39919 8.8 HIGH wifi: mt76: mt7996: add missing check for rx wcid entries
CVE-2025-39918 8.8 HIGH wifi: mt76: fix linked list corruption
CVE-2023-53454 8.8 HIGH HID: multitouch: Correct devm device reference for hidinput input_dev name
CVE-2022-50442 8.4 HIGH fs/ntfs3: Validate buffer length while parsing index
CVE-2023-53493 8.4 HIGH accel/qaic: tighten bounds checking in decode_message()
CVE-2023-53492 7.8 HIGH netfilter: nf_tables: do not ignore genmask when looking up chain by id
CVE-2025-39924 7.8 HIGH erofs: fix invalid algorithm for encoded extents
CVE-2023-53510 7.8 HIGH scsi: ufs: core: Fix handling of lrbp->cmd
CVE-2025-39927 7.8 HIGH ceph: fix race condition validating r_parent before applying state
CVE-2022-50421 7.8 HIGH rpmsg: char: Avoid double destroy of default endpoint
CVE-2023-53506 7.8 HIGH udf: Do not bother merging very long extents
CVE-2022-50423 7.8 HIGH ACPICA: Fix use-after-free in acpi_ut_copy_ipackage_to_ipackage()
CVE-2023-53504 7.8 HIGH RDMA/bnxt_re: Properly order ib_device_unalloc() to avoid UAF
CVE-2023-53495 7.8 HIGH net: ethernet: mvpp2_main: fix possible OOB write in mvpp2_ethtool_get_rxnfc()
CVE-2023-53494 7.8 HIGH crypto: xts - Handle EBUSY correctly
CVE-2022-50437 7.8 HIGH drm/msm/hdmi: fix memory corruption with too many bridges
CVE-2023-53478 7.8 HIGH tracing/synthetic: Fix races on freeing last_cmd
CVE-2023-53481 7.8 HIGH ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed
CVE-2023-53486 7.8 HIGH fs/ntfs3: Enhance the attribute size check

Showing top 20 of 169 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-39899

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