VULNERABILITY

Ubuntu: (Multiple Advisories) (CVE-2025-21756): Linux kernel vulnerabilities

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Ubuntu: (Multiple Advisories) (CVE-2025-21756): Linux kernel vulnerabilities

Severity

CVSS

(AV:L/AC:L/Au:S/C:C/I:C/A:C)

Published

02/27/2025

Created

04/25/2025

Added

04/24/2025

Modified

05/27/2025

Description

In the Linux kernel, the following vulnerability has been resolved: vsock: Keep the binding until socket destruction Preserve sockets bindings; this includes both resulting from an explicit bind() and those implicitly bound through autobind during connect(). Prevents socket unbinding during a transport reassignment, which fixes a use-after-free: 1. vsock_create() (refcnt=1) calls vsock_insert_unbound() (refcnt=2) 2. transport->release() calls vsock_remove_bound() without checking if sk was bound and moved to bound list (refcnt=1) 3. vsock_bind() assumes sk is in unbound list and before __vsock_insert_bound(vsock_bound_sockets()) calls __vsock_remove_bound() which does: list_del_init(&vsk->bound_table); // nop sock_put(&vsk->sk); // refcnt=0 BUG: KASAN: slab-use-after-free in __vsock_bind+0x62e/0x730 Read of size 4 at addr ffff88816b46a74c by task a.out/2057 dump_stack_lvl+0x68/0x90 print_report+0x174/0x4f6 kasan_report+0xb9/0x190 __vsock_bind+0x62e/0x730 vsock_bind+0x97/0xe0 __sys_bind+0x154/0x1f0 __x64_sys_bind+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Allocated by task 2057: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 __kasan_slab_alloc+0x85/0x90 kmem_cache_alloc_noprof+0x131/0x450 sk_prot_alloc+0x5b/0x220 sk_alloc+0x2c/0x870 __vsock_create.constprop.0+0x2e/0xb60 vsock_create+0xe4/0x420 __sock_create+0x241/0x650 __sys_socket+0xf2/0x1a0 __x64_sys_socket+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 2057: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x37/0x60 __kasan_slab_free+0x4b/0x70 kmem_cache_free+0x1a1/0x590 __sk_destruct+0x388/0x5a0 __vsock_bind+0x5e1/0x730 vsock_bind+0x97/0xe0 __sys_bind+0x154/0x1f0 __x64_sys_bind+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e refcount_t: addition on 0; use-after-free. WARNING: CPU: 7 PID: 2057 at lib/refcount.c:25 refcount_warn_saturate+0xce/0x150 RIP: 0010:refcount_warn_saturate+0xce/0x150 __vsock_bind+0x66d/0x730 vsock_bind+0x97/0xe0 __sys_bind+0x154/0x1f0 __x64_sys_bind+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e refcount_t: underflow; use-after-free. WARNING: CPU: 7 PID: 2057 at lib/refcount.c:28 refcount_warn_saturate+0xee/0x150 RIP: 0010:refcount_warn_saturate+0xee/0x150 vsock_remove_bound+0x187/0x1e0 __vsock_release+0x383/0x4a0 vsock_release+0x90/0x120 __sock_release+0xa3/0x250 sock_close+0x14/0x20 __fput+0x359/0xa80 task_work_run+0x107/0x1d0 do_exit+0x847/0x2560 do_group_exit+0xb8/0x250 __x64_sys_exit_group+0x3a/0x50 x64_sys_call+0xfec/0x14f0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Solution(s)

ubuntu-upgrade-linux-image-5-15-0-1023-nvidia-tegra-igx
ubuntu-upgrade-linux-image-5-15-0-1023-nvidia-tegra-igx-rt
ubuntu-upgrade-linux-image-5-15-0-1035-nvidia-tegra
ubuntu-upgrade-linux-image-5-15-0-1035-nvidia-tegra-rt
ubuntu-upgrade-linux-image-5-15-0-1046-xilinx-zynqmp
ubuntu-upgrade-linux-image-5-15-0-1064-gkeop
ubuntu-upgrade-linux-image-5-15-0-1074-ibm
ubuntu-upgrade-linux-image-5-15-0-1075-intel-iot-realtime
ubuntu-upgrade-linux-image-5-15-0-1076-nvidia
ubuntu-upgrade-linux-image-5-15-0-1076-nvidia-lowlatency
ubuntu-upgrade-linux-image-5-15-0-1076-raspi
ubuntu-upgrade-linux-image-5-15-0-1077-intel-iotg
ubuntu-upgrade-linux-image-5-15-0-1078-kvm
ubuntu-upgrade-linux-image-5-15-0-1079-gke
ubuntu-upgrade-linux-image-5-15-0-1079-oracle
ubuntu-upgrade-linux-image-5-15-0-1081-gcp
ubuntu-upgrade-linux-image-5-15-0-1081-gcp-fips
ubuntu-upgrade-linux-image-5-15-0-1082-aws
ubuntu-upgrade-linux-image-5-15-0-1082-aws-fips
ubuntu-upgrade-linux-image-5-15-0-1082-realtime
ubuntu-upgrade-linux-image-5-15-0-1087-azure
ubuntu-upgrade-linux-image-5-15-0-1087-azure-fde
ubuntu-upgrade-linux-image-5-15-0-1087-azure-fips
ubuntu-upgrade-linux-image-5-15-0-138-fips
ubuntu-upgrade-linux-image-5-15-0-138-generic
ubuntu-upgrade-linux-image-5-15-0-138-generic-64k
ubuntu-upgrade-linux-image-5-15-0-138-generic-lpae
ubuntu-upgrade-linux-image-5-15-0-138-lowlatency
ubuntu-upgrade-linux-image-5-15-0-138-lowlatency-64k
ubuntu-upgrade-linux-image-6-11-0-1008-realtime
ubuntu-upgrade-linux-image-6-11-0-1011-raspi
ubuntu-upgrade-linux-image-6-11-0-1012-aws
ubuntu-upgrade-linux-image-6-11-0-1012-lowlatency
ubuntu-upgrade-linux-image-6-11-0-1012-lowlatency-64k
ubuntu-upgrade-linux-image-6-11-0-1013-azure
ubuntu-upgrade-linux-image-6-11-0-1013-azure-fde
ubuntu-upgrade-linux-image-6-11-0-1013-gcp
ubuntu-upgrade-linux-image-6-11-0-1013-gcp-64k
ubuntu-upgrade-linux-image-6-11-0-1014-oracle
ubuntu-upgrade-linux-image-6-11-0-1014-oracle-64k
ubuntu-upgrade-linux-image-6-11-0-1020-oem
ubuntu-upgrade-linux-image-6-11-0-24-generic
ubuntu-upgrade-linux-image-6-11-0-24-generic-64k
ubuntu-upgrade-linux-image-6-8-0-1010-gkeop
ubuntu-upgrade-linux-image-6-8-0-1014-azure-nvidia
ubuntu-upgrade-linux-image-6-8-0-1023-gke
ubuntu-upgrade-linux-image-6-8-0-1024-ibm
ubuntu-upgrade-linux-image-6-8-0-1024-oracle
ubuntu-upgrade-linux-image-6-8-0-1024-oracle-64k
ubuntu-upgrade-linux-image-6-8-0-1026-nvidia
ubuntu-upgrade-linux-image-6-8-0-1026-nvidia-64k
ubuntu-upgrade-linux-image-6-8-0-1026-nvidia-lowlatency
ubuntu-upgrade-linux-image-6-8-0-1026-nvidia-lowlatency-64k
ubuntu-upgrade-linux-image-6-8-0-1026-oem
ubuntu-upgrade-linux-image-6-8-0-1027-aws
ubuntu-upgrade-linux-image-6-8-0-1027-azure
ubuntu-upgrade-linux-image-6-8-0-1027-azure-fde
ubuntu-upgrade-linux-image-6-8-0-1028-gcp
ubuntu-upgrade-linux-image-6-8-0-1028-gcp-64k
ubuntu-upgrade-linux-image-6-8-0-1028-raspi
ubuntu-upgrade-linux-image-6-8-0-2023-raspi-realtime
ubuntu-upgrade-linux-image-6-8-0-58-generic
ubuntu-upgrade-linux-image-6-8-0-58-generic-64k
ubuntu-upgrade-linux-image-6-8-0-58-lowlatency
ubuntu-upgrade-linux-image-6-8-0-58-lowlatency-64k
ubuntu-upgrade-linux-image-6-8-1-1020-realtime
ubuntu-upgrade-linux-image-aws
ubuntu-upgrade-linux-image-aws-fips
ubuntu-upgrade-linux-image-aws-lts-22-04
ubuntu-upgrade-linux-image-aws-lts-24-04
ubuntu-upgrade-linux-image-azure
ubuntu-upgrade-linux-image-azure-cvm
ubuntu-upgrade-linux-image-azure-fde
ubuntu-upgrade-linux-image-azure-fde-lts-22-04
ubuntu-upgrade-linux-image-azure-fde-lts-24-04
ubuntu-upgrade-linux-image-azure-fips
ubuntu-upgrade-linux-image-azure-lts-22-04
ubuntu-upgrade-linux-image-azure-lts-24-04
ubuntu-upgrade-linux-image-azure-nvidia
ubuntu-upgrade-linux-image-fips
ubuntu-upgrade-linux-image-gcp
ubuntu-upgrade-linux-image-gcp-64k
ubuntu-upgrade-linux-image-gcp-64k-lts-24-04
ubuntu-upgrade-linux-image-gcp-fips
ubuntu-upgrade-linux-image-gcp-lts-22-04
ubuntu-upgrade-linux-image-gcp-lts-24-04
ubuntu-upgrade-linux-image-generic
ubuntu-upgrade-linux-image-generic-64k
ubuntu-upgrade-linux-image-generic-64k-hwe-20-04
ubuntu-upgrade-linux-image-generic-64k-hwe-22-04
ubuntu-upgrade-linux-image-generic-64k-hwe-24-04
ubuntu-upgrade-linux-image-generic-hwe-20-04
ubuntu-upgrade-linux-image-generic-hwe-22-04
ubuntu-upgrade-linux-image-generic-hwe-24-04
ubuntu-upgrade-linux-image-generic-lpae
ubuntu-upgrade-linux-image-generic-lpae-hwe-20-04
ubuntu-upgrade-linux-image-gke
ubuntu-upgrade-linux-image-gke-5-15
ubuntu-upgrade-linux-image-gkeop
ubuntu-upgrade-linux-image-gkeop-5-15
ubuntu-upgrade-linux-image-gkeop-6-8
ubuntu-upgrade-linux-image-ibm
ubuntu-upgrade-linux-image-ibm-classic
ubuntu-upgrade-linux-image-ibm-lts-24-04
ubuntu-upgrade-linux-image-intel
ubuntu-upgrade-linux-image-intel-iot-realtime
ubuntu-upgrade-linux-image-intel-iotg
ubuntu-upgrade-linux-image-kvm
ubuntu-upgrade-linux-image-lowlatency
ubuntu-upgrade-linux-image-lowlatency-64k
ubuntu-upgrade-linux-image-lowlatency-64k-hwe-20-04
ubuntu-upgrade-linux-image-lowlatency-64k-hwe-22-04
ubuntu-upgrade-linux-image-lowlatency-64k-hwe-24-04
ubuntu-upgrade-linux-image-lowlatency-hwe-20-04
ubuntu-upgrade-linux-image-lowlatency-hwe-22-04
ubuntu-upgrade-linux-image-lowlatency-hwe-24-04
ubuntu-upgrade-linux-image-nvidia
ubuntu-upgrade-linux-image-nvidia-6-8
ubuntu-upgrade-linux-image-nvidia-64k
ubuntu-upgrade-linux-image-nvidia-64k-6-8
ubuntu-upgrade-linux-image-nvidia-64k-hwe-22-04
ubuntu-upgrade-linux-image-nvidia-hwe-22-04
ubuntu-upgrade-linux-image-nvidia-lowlatency
ubuntu-upgrade-linux-image-nvidia-lowlatency-64k
ubuntu-upgrade-linux-image-nvidia-tegra
ubuntu-upgrade-linux-image-nvidia-tegra-igx
ubuntu-upgrade-linux-image-nvidia-tegra-igx-rt
ubuntu-upgrade-linux-image-nvidia-tegra-rt
ubuntu-upgrade-linux-image-oem-20-04
ubuntu-upgrade-linux-image-oem-20-04b
ubuntu-upgrade-linux-image-oem-20-04c
ubuntu-upgrade-linux-image-oem-20-04d
ubuntu-upgrade-linux-image-oem-22-04
ubuntu-upgrade-linux-image-oem-22-04a
ubuntu-upgrade-linux-image-oem-22-04b
ubuntu-upgrade-linux-image-oem-22-04c
ubuntu-upgrade-linux-image-oem-22-04d
ubuntu-upgrade-linux-image-oem-24-04
ubuntu-upgrade-linux-image-oem-24-04a
ubuntu-upgrade-linux-image-oem-24-04b
ubuntu-upgrade-linux-image-oracle
ubuntu-upgrade-linux-image-oracle-64k
ubuntu-upgrade-linux-image-oracle-64k-lts-24-04
ubuntu-upgrade-linux-image-oracle-lts-22-04
ubuntu-upgrade-linux-image-oracle-lts-24-04
ubuntu-upgrade-linux-image-raspi
ubuntu-upgrade-linux-image-raspi-nolpae
ubuntu-upgrade-linux-image-raspi-realtime
ubuntu-upgrade-linux-image-realtime
ubuntu-upgrade-linux-image-realtime-hwe-24-04
ubuntu-upgrade-linux-image-virtual
ubuntu-upgrade-linux-image-virtual-hwe-20-04
ubuntu-upgrade-linux-image-virtual-hwe-22-04
ubuntu-upgrade-linux-image-virtual-hwe-24-04
ubuntu-upgrade-linux-image-xilinx-zynqmp

References

https://attackerkb.com/topics/cve-2025-21756
CVE - 2025-21756
USN-7445-1
USN-7448-1
USN-7449-1
USN-7449-2
USN-7450-1
USN-7451-1
USN-7452-1
USN-7453-1
USN-7455-1
USN-7455-2
USN-7455-3
USN-7455-4
USN-7455-5
USN-7459-1
USN-7459-2
USN-7460-1
USN-7468-1
USN-7475-1
USN-7523-1
USN-7524-1
https://git.kernel.org/linus/fcdd2242c0231032fc84e1404315c245ae56322a
https://git.kernel.org/stable/c/3f43540166128951cc1be7ab1ce6b7f05c670d8b
https://git.kernel.org/stable/c/645ce25aa0e67895b11d89f27bb86c9d444c40f8
https://git.kernel.org/stable/c/b1afd40321f1c243cffbcf40ea7ca41aca87fa5e
https://git.kernel.org/stable/c/fcdd2242c0231032fc84e1404315c245ae56322a
https://ubuntu.com/security/notices/USN-7445-1
https://ubuntu.com/security/notices/USN-7448-1
https://ubuntu.com/security/notices/USN-7449-1
https://ubuntu.com/security/notices/USN-7450-1
https://ubuntu.com/security/notices/USN-7451-1
https://ubuntu.com/security/notices/USN-7452-1
https://ubuntu.com/security/notices/USN-7453-1
https://www.cve.org/CVERecord?id=CVE-2025-21756

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VULNERABILITY

Ubuntu: (Multiple Advisories) (CVE-2025-21756): Linux kernel vulnerabilities

Ubuntu: (Multiple Advisories) (CVE-2025-21756): Linux kernel vulnerabilities

Description

Solution(s)

References

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