7.8 CVE-2025-21756

Patch
 

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
https://nvd.nist.gov/vuln/detail/CVE-2025-21756

Categories

CWE-416 : Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. If the product accesses a previously-freed pointer, then it means that a separate weakness or error already occurred previously, such as a race condition, an unexpected or poorly handled error condition, confusion over which part of the program is responsible for freeing the memory, performing the free too soon, etc. a pointer that no longer points to valid memory, often after it has been freed commonly used acronym for Use After Free Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Choose a language that provides automatic memory management. When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy. Chain: an operating system kernel has insufficent resource locking (CWE-413) leading to a use after free (CWE-416). Chain: two threads in a web browser use the same resource (CWE-366), but one of those threads can destroy the resource before the other has completed (CWE-416). Chain: mobile platform race condition (CWE-362) leading to use-after-free (CWE-416), as exploited in the wild per CISA KEV. Chain: race condition (CWE-362) leads to use-after-free (CWE-416), as exploited in the wild per CISA KEV. Use-after-free triggered by closing a connection while data is still being transmitted. Improper allocation for invalid data leads to use-after-free. certificate with a large number of Subject Alternate Names not properly handled in realloc, leading to use-after-free Timers are not disabled when a related object is deleted Access to a "dead" object that is being cleaned up object is deleted even with a non-zero reference count, and later accessed use-after-free involving request containing an invalid version number unload of an object that is currently being accessed by other functionality incorrectly tracking a reference count leads to use-after-free use-after-free related to use of uninitialized memory HTML document with incorrectly-nested tags Use after free in ActiveX object by providing a malformed argument to a method use-after-free by disconnecting during data transfer, or a message containing incorrect data types disconnect during a large data transfer causes incorrect reference count, leading to use-after-free use-after-free found by fuzzing Chain: race condition (CWE-362) from improper handling of a page transition in web client while an applet is loading (CWE-368) leads to use after free (CWE-416) realloc generates new buffer and pointer, but previous pointer is still retained, leading to use after free Use-after-free in web browser, probably resultant from not initializing memory. use-after-free when one thread accessed memory that was freed by another thread assignment of malformed values to certain properties triggers use after free mail server does not properly handle a long header. chain: integer overflow leads to use-after-free freed pointer dereference Chain: A multi-threaded race condition (CWE-367) allows attackers to cause two threads to process the same RPC request, which causes a use-after-free (CWE-416) in one thread

References


 

CPE

cpe start end
Configuration 1
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 5.5 < 5.10.235
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 5.11 < 5.15.179
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 5.16 < 6.1.131
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.2 < 6.6.79
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.7 < 6.12.16
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* >= 6.13 < 6.13.4

REMEDIATION

Patch

Url
https://git.kernel.org/stable/c/3f43540166128951cc1be7ab1ce6b7f05c670d8b
https://git.kernel.org/stable/c/42b33381e5e1f2b967dc4fb4221ddb9aaf10d197
https://git.kernel.org/stable/c/645ce25aa0e67895b11d89f27bb86c9d444c40f8
https://git.kernel.org/stable/c/b1afd40321f1c243cffbcf40ea7ca41aca87fa5e
https://git.kernel.org/stable/c/e48fcb403c2d0e574c19683f09399ab4cf67809c
https://git.kernel.org/stable/c/e7754d564579a5db9c5c9f74228df5d6dd6f1173
https://git.kernel.org/stable/c/fcdd2242c0231032fc84e1404315c245ae56322a

EXPLOITS

Exploit-db.com

id description date
No known exploits

POC Github

Url
No known exploits

Other Nist (github, ...)

Url
No known exploits

CAPEC

Common Attack Pattern Enumerations and Classifications

id description severity
No entry