amt: Don't support cross-netns setup.

Description

In the Linux kernel, the following vulnerability has been resolved: amt: Don't support cross-netns setup. When a lower device is unregistered, amt_device_event() tries to unregister its upper AMT device, but it has two problems. 1. amt_lookup_upper_dev() looks up an upper device in the lower device's netns only 2. amt_device_event() unregisters a single upper device only If AMT device is created on a lower device in another netns, removing the lower device triggers the splat below and gets stuck until all upper devices are removed. [0] The cross-netns setup seems unintentional considering 1. and the following points: * amt_link_setup() sets dev->netns_immutable to true * skb_scrub_packet() is not called in the fast path * iproute2 binary fails to find cross-netns lower device via link-netns: # ip -n ns1 link add amt0 link-netns ns2 type amt dev veth1 Cannot find device "veth1" Instead of supporting it properly and preparing for per-netns netdev unreg, let's forbid cross-netns setup. Note that the problem 2. needs a separate fix. [0]: WARNING: net/core/dev.c:12518 at unregister_netdevice_many_notify+0x1cce/0x2250, CPU#48: ip/2031 Modules linked in: CPU: 48 UID: 0 PID: 2031 Comm: ip Not tainted 7.2.0-rc5+ #27 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 RIP: 0010:unregister_netdevice_many_notify (net/core/dev.c:12518) Code: 89 ef e8 d5 52 ae fe e9 d0 f4 ff ff 48 8d 3d f9 3b 9c 02 48 c7 c6 c0 0b 63 84 ba ab 1f 00 00 67 48 0f b9 3a e9 65 ff ff ff 90 <0f> 0b 90 eb 81 48 8d 3d f6 3b 9c 02 48 c7 c6 c0 0b 63 84 ba e2 1f RSP: 0018:ffffc90004abf160 EFLAGS: 00010212 RAX: ffff888104d38260 RBX: ffff88800b0911b8 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff85b9f880 RBP: ffffc90004abf2d0 R08: ffffffff85b9f887 R09: 1ffffffff0b73f10 R10: dffffc0000000000 R11: fffffbfff0b73f11 R12: ffff88800b091d08 R13: ffff88800b091178 R14: dffffc0000000000 R15: ffff88800b091000 FS: 00007f555b86c600(0000) GS:ffff8881942a0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562107d489c0 CR3: 0000000109a40002 CR4: 0000000000372ef0 Call Trace: <TASK> rtnl_dellink (net/core/rtnetlink.c:3632 net/core/rtnetlink.c:3674) rtnetlink_rcv_msg (net/core/rtnetlink.c:7112) netlink_rcv_skb (net/netlink/af_netlink.c:2556) netlink_unicast (net/netlink/af_netlink.c:1319) netlink_sendmsg (net/netlink/af_netlink.c:1900) ____sys_sendmsg (net/socket.c:775) __sys_sendmsg (net/socket.c:2738) do_syscall_64 (arch/x86/entry/syscall_64.c:63) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) ... unregister_netdevice: waiting for veth0 to become free. Usage count = 7 ref_tracker: netdev@ffff88800d7496d8 has 3/3 users at __netdev_adjacent_dev_insert (./include/linux/netdevice.h:4525 ./include/linux/netdevice.h:4554 net/core/dev.c:8791) __netdev_upper_dev_link (net/core/dev.c:8879 net/core/dev.c:8963) netdev_upper_dev_link (net/core/dev.c:9009) amt_newlink (drivers/net/amt.c:3321)

Timeline

Scores

No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.

EPSS (exploitation in 30 days)

0.21% · top 88% of all CVEs (11 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.

Affected products

• Linux · Linux

  • affected b9022b53adad88fd6cf2b9718c9e498504f3e1dd – < 2a5a578d2e13d2dd6c1b272be7cfa0a6dd64552c
  • affected b9022b53adad88fd6cf2b9718c9e498504f3e1dd – < a457ff1189f22c2f15f69df55dc910b8b6d7a77d
  • affected b9022b53adad88fd6cf2b9718c9e498504f3e1dd – < 5ebaad6cf2a639afbf0b265f9a7d1fb6f656a37e
  • affected b9022b53adad88fd6cf2b9718c9e498504f3e1dd – < 569eb11f0990849ba48706a2bfa743273707e254
  • affected b9022b53adad88fd6cf2b9718c9e498504f3e1dd – < e1dc0af719a2566ae7ccb82c0a11f70aa54908e9
  • affected b9022b53adad88fd6cf2b9718c9e498504f3e1dd – < e99ecc3046ea5f5c6b5e1f8b4ef854c6c6998e06

• Linux · Linux

  • affected 5.16
  • unaffected < 5.16
  • unaffected 6.1.191 – ≤ 6.1.*
  • unaffected 6.6.160 – ≤ 6.6.*
  • unaffected 6.12.114 – ≤ 6.12.*
  • unaffected 6.18.52 – ≤ 6.18.*
  • unaffected 7.2.6 – ≤ 7.2.*
  • unaffected 7.3 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-81825 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-90232](https://cveledger.app/badge/CVE-2026-90232.svg)](https://cveledger.app/cve/CVE-2026-90232)

Record last updated 30 Oct 2026, 12:34 UTC.