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CVE-2025-21696— mm: clear uffd-wp PTE/PMD state on mremap()

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，该漏洞源于在mremap()操作中未清除uffd-wp PTE/PMD状态。攻击者利用该漏洞可以导致vma标志与pte/pmd标志不匹配，触发警告。

AI Predicted 5.5 Difficulty: Easy EPSS 0.19% · P9

Possible ATT&CK Techniques 1 AI

T1564 · Hide Artifacts

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03< 310ac886d68de661c3a334198d8604b722d7fdf8 affected
63b2d4174c4ad1f40b48d7138e71bcb564c1fe03< 0cef0bb836e3cfe00f08f9606c72abd72fe78ca3 affected
5.7 affected
< 5.7 unaffected
6.12.11≤ 6.12.* unaffected
6.13≤ * unaffected
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I. Basic Information for CVE-2025-21696

Vulnerability Information
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Vulnerability Title
mm: clear uffd-wp PTE/PMD state on mremap()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mm: clear uffd-wp PTE/PMD state on mremap() When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set. Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.
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，该漏洞源于在mremap()操作中未清除uffd-wp PTE/PMD状态。攻击者利用该漏洞可以导致vma标志与pte/pmd标志不匹配，触发警告。
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 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 ~ 310ac886d68de661c3a334198d8604b722d7fdf8 -
Linux Linux 5.7 -

II. Public POCs for CVE-2025-21696

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III. Intelligence Information for CVE-2025-21696

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Patches & Fixes for CVE-2025-21696 (2)

Same Patch Batch · Linux · 2025-02-12 · 7 CVEs total

CVE-2025-21697 7.8 HIGH drm/v3d: Ensure job pointer is set to NULL after job completion
CVE-2025-21699 7.8 HIGH gfs2: Truncate address space when flipping GFS2_DIF_JDATA flag
CVE-2024-57952 7.1 HIGH Revert "libfs: fix infinite directory reads for offset dir"
CVE-2024-57951 hrtimers: Handle CPU state correctly on hotplug
CVE-2025-21694 fs/proc: fix softlockup in __read_vmcore (part 2)
CVE-2025-21695 platform/x86: dell-uart-backlight: fix serdev race

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21696

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