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CVE-2026-74615

vxlan: do not arm the ageing timer on a device that is down

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

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>

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux 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 Linux

    5.0

  • KernelLinux

    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

References 8

git.kernel.org