CVE-2022-50163 ax25: fix incorrect dev_tracker usage

High 7.8 Published 18 Jun 2025 Updated 23 May 2026

A use-after-free vulnerability in the Linux kernel AX.25 subsystem can cause a system crash when reference tracking is enabled.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2022-50163?

CVE-2022-50163 is a high-severity use after free vulnerability in Linux kernel, published on 18 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

ax25: fix incorrect dev_tracker usage

While investigating a separate rose issue [1], and enabling CONFIG_NET_DEV_REFCNT_TRACKER=y, Bernard reported an orthogonal ax25 issue [2]

An ax25_dev can be used by one (or many) struct ax25_cb. We thus need different dev_tracker, one per struct ax25_cb.

After this patch is applied, we are able to focus on rose.

[1] https://lore.kernel.org/netdev/[email protected]/

[2] [ 205.798723] reference already released. [ 205.798732] allocated in: [ 205.798734] ax25_bind+0x1a2/0x230 [ax25] [ 205.798747] __sys_bind+0xea/0x110 [ 205.798753] __x64_sys_bind+0x18/0x20 [ 205.798758] do_syscall_64+0x5c/0x80 [ 205.798763] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 205.798768] freed in: [ 205.798770] ax25_release+0x115/0x370 [ax25] [ 205.798778] __sock_release+0x42/0xb0 [ 205.798782] sock_close+0x15/0x20 [ 205.798785] __fput+0x9f/0x260 [ 205.798789] ____fput+0xe/0x10 [ 205.798792] task_work_run+0x64/0xa0 [ 205.798798] exit_to_user_mode_prepare+0x18b/0x190 [ 205.798804] syscall_exit_to_user_mode+0x26/0x40 [ 205.798808] do_syscall_64+0x69/0x80 [ 205.798812] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 205.798827] ------------[ cut here ]------------ [ 205.798829] WARNING: CPU: 2 PID: 2605 at lib/ref_tracker.c:136 ref_tracker_free.cold+0x60/0x81 [ 205.798837] Modules linked in: rose netrom mkiss ax25 rfcomm cmac algif_hash algif_skcipher af_alg bnep snd_hda_codec_hdmi nls_iso8859_1 i915 rtw88_8821ce rtw88_8821c x86_pkg_temp_thermal rtw88_pci intel_powerclamp rtw88_core snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio coretemp snd_hda_intel kvm_intel snd_intel_dspcfg mac80211 snd_hda_codec kvm i2c_algo_bit drm_buddy drm_dp_helper btusb drm_kms_helper snd_hwdep btrtl snd_hda_core btbcm joydev crct10dif_pclmul btintel crc32_pclmul ghash_clmulni_intel mei_hdcp btmtk intel_rapl_msr aesni_intel bluetooth input_leds snd_pcm crypto_simd syscopyarea processor_thermal_device_pci_legacy sysfillrect cryptd intel_soc_dts_iosf snd_seq sysimgblt ecdh_generic fb_sys_fops rapl libarc4 processor_thermal_device intel_cstate processor_thermal_rfim cec snd_timer ecc snd_seq_device cfg80211 processor_thermal_mbox mei_me processor_thermal_rapl mei rc_core at24 snd intel_pch_thermal intel_rapl_common ttm soundcore int340x_thermal_zone video [ 205.798948] mac_hid acpi_pad sch_fq_codel ipmi_devintf ipmi_msghandler drm msr parport_pc ppdev lp parport ramoops pstore_blk reed_solomon pstore_zone efi_pstore ip_tables x_tables autofs4 hid_generic usbhid hid i2c_i801 i2c_smbus r8169 xhci_pci ahci libahci realtek lpc_ich xhci_pci_renesas [last unloaded: ax25] [ 205.798992] CPU: 2 PID: 2605 Comm: ax25ipd Not tainted 5.18.11-F6BVP #3 [ 205.798996] Hardware name: To be filled by O.E.M. To be filled by O.E.M./CK3, BIOS 5.011 09/16/2020 [ 205.798999] RIP: 0010:ref_tracker_free.cold+0x60/0x81 [ 205.799005] Code: e8 d2 01 9b ff 83 7b 18 00 74 14 48 c7 c7 2f d7 ff 98 e8 10 6e fc ff 8b 7b 18 e8 b8 01 9b ff 4c 89 ee 4c 89 e7 e8 5d fd 07 00 <0f> 0b b8 ea ff ff ff e9 30 05 9b ff 41 0f b6 f7 48 c7 c7 a0 fa 4e [ 205.799008] RSP: 0018:ffffaf5281073958 EFLAGS: 00010286 [ 205.799011] RAX: 0000000080000000 RBX: ffff9a0bd687ebe0 RCX: 0000000000000000 [ 205.799014] RDX: 0000000000000001 RSI: 0000000000000282 RDI: 00000000ffffffff [ 205.799016] RBP: ffffaf5281073a10 R08: 0000000000000003 R09: fffffffffffd5618 [ 205.799019] R10: 0000000000ffff10 R11: 000000000000000f R12: ffff9a0bc53384d0 [ 205.799022] R13: 0000000000000282 R14: 00000000ae000001 R15: 0000000000000001 [ 205.799024] FS: 0000000000000000(0000) GS:ffff9a0d0f300000(0000) knlGS:0000000000000000 [ 205.799028] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 205.799031] CR2: 00007ff6b8311554 CR3: 000000001ac10004 CR4: 00000000001706e0 [ 205.799033] Call Trace: [ 205.799035] <TASK> [ 205.799038] ? ax25_dev_device_down+0xd9/ ---truncated---

Which versions are affected by CVE-2022-50163?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2022-50163?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2022-50163 being exploited?

There is no known exploitation of CVE-2022-50163 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as DEBIAN-CVE-2022-50163, GHSA-qv7x-xghp-vpfc, ROOT-OS-DEBIAN-11-CVE-2022-50163, ROOT-OS-UBUNTU-2204-CVE-2022-50163, UBUNTU-CVE-2022-50163.