CVE-2026-53199hv_netvsc: use kmap_local_page in netvsc_copy_to_send_buf

Description

In the Linux kernel, the following vulnerability has been resolved: hv_netvsc: use kmap_local_page in netvsc_copy_to_send_buf netvsc_copy_to_send_buf() copies page buffer entries into the VMBus send buffer using phys_to_virt() on the entry PFN. Entries for the RNDIS header and the skb linear data come from kmalloc'd memory and are always in the kernel direct map, but entries for skb fragments reference page cache or user pages, which on 32-bit x86 with CONFIG_HIGHMEM=y can live above the LOWMEM boundary. For such a page phys_to_virt() returns an address outside the direct map and the subsequent memcpy() faults on the transmit softirq path, which is fatal. Map the pages with kmap_local_page() instead, handling two properties of the page buffer entries: - pb[i].pfn is a Hyper-V PFN at HV_HYP_PAGE_SIZE (4K) granularity, not a native PFN. Reconstruct the physical address first and derive the native page from it, so the mapping stays correct where PAGE_SIZE > HV_HYP_PAGE_SIZE (e.g. arm64 with 64K pages). - Since commit 41a6328b2c55 ("hv_netvsc: Preserve contiguous PFN grouping in the page buffer array"), an entry describes a full physically contiguous fragment and pb[i].len can exceed PAGE_SIZE, while kmap_local_page() maps a single page. Copy page by page, splitting at native page boundaries. The copy path only handles packets smaller than the send section size (6144 bytes by default); larger packets take the cp_partial path where only the RNDIS header is copied. So entries here are bounded by the section size and a copy is split at most once on 4K-page systems. On !CONFIG_HIGHMEM configs kmap_local_page() folds to page_address() and no mapping work is added.

Timeline

Scores

EPSS (exploitation in 30 days)

0.50% · top 56% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Affected products

• Linux · Linux

  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < 16514afeb7d3d121072ba9a0b640d6c1c5507db0
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < a82d4251918f37d9c5aab7b365157669fb885ec3
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < 695c59cf7bf707e6ff8cea01916ee50e86616933
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < 09b8a7aa5a341bb345dc492aac139525efa13515
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < 918c0c988239aa5ab96b254e504d191af6191061
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < 0b38870d81ab3a04c1ab0598d9d3285f5d9d0584
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < fe7221b4346418d27ec2daccfc09df6692b76f0b
  • affected c25aaf814a63f9d9c4e45416f13d70ef0aa0be2e – < 004e9ecfe6c5384f9e0b2f6f6389d42ec22789af

• Linux · Linux

  • affected 3.16
  • unaffected < 3.16
  • unaffected 5.10.259 – ≤ 5.10.*
  • unaffected 5.15.210 – ≤ 5.15.*
  • unaffected 6.1.176 – ≤ 6.1.*
  • unaffected 6.6.143 – ≤ 6.6.*
  • unaffected 6.12.94 – ≤ 6.12.*
  • unaffected 6.18.36 – ≤ 6.18.*
  • unaffected 7.0.13 – ≤ 7.0.*
  • unaffected 7.1 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-39290 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-53199](https://cveledger.app/badge/CVE-2026-53199.svg)](https://cveledger.app/cve/CVE-2026-53199)

Record last updated 19 Oct 2026, 19:57 UTC.