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CVE-2026-31787— xen/privcmd: fix double free via VMA splitting

EPSS 0.01% · P2
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I. Basic Information for CVE-2026-31787

Vulnerability Information
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Vulnerability Title
xen/privcmd: fix double free via VMA splitting
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: fix double free via VMA splitting privcmd_vm_ops defines .close (privcmd_close), but neither .may_split nor .open. When userspace does a partial munmap() on a privcmd mapping, the kernel splits the VMA via __split_vma(). Since may_split is NULL, the split is allowed. vm_area_dup() copies vm_private_data (a pages array allocated in alloc_empty_pages()) into the new VMA without any fixup, because there is no .open callback. Both VMAs now point to the same pages array. When the unmapped portion is closed, privcmd_close() calls: - xen_unmap_domain_gfn_range() - xen_free_unpopulated_pages() - kvfree(pages) The surviving VMA still holds the dangling pointer. When it is later destroyed, the same sequence runs again, which leads to a double free. Fix this issue by adding a .may_split callback denying the VMA split. This is XSA-487 / CVE-2026-31787
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
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xen privcmd驱动中VMA分割导致双重释放，可能导致内存损坏。
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

VendorProductAffected VersionsCPESubscribe
LinuxLinux d71f513985c22f1050295d1a7e4327cf9fb060da ~ dbf862ce9f009128ab86b234d91413a3e450beb4 -
LinuxLinux 3.8 -

II. Public POCs for CVE-2026-31787

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III. Intelligence Information for CVE-2026-31787

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Same Patch Batch · Linux · 2026-04-30 · 4 CVEs total

CVE-2026-316937.8 HIGHcifs: some missing initializations on replay
CVE-2026-317867.8 HIGHBuffer overflow in drivers/xen/sys-hypervisor.c
CVE-2026-31692rtnetlink: add missing netlink_ns_capable() check for peer netns

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31787

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