---
cve: "CVE-2026-74615"
severity: "HIGH"
cvss: 8.8
epss: "24.5%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-08-22 16:16:34"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T09:17:51+02:00"
---

# CVE-2026-74615

> 8.8 HIGH

## Beschreibung

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

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.10.265
- Kernel ≥ 5.15.216
- Kernel ≥ 6.1.183
- Kernel ≥ 6.6.152
- Kernel ≥ 6.12.104
- Kernel ≥ 6.18.45
- Kernel ≥ 7.1.9

## Referenzen

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

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74615) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_