HIGH
smb LoginRequest Leak
CVE-2026-90175
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
01Description
In the Linux kernel, the following vulnerability has been resolved: smb: server: fix leak of ksmbd_ipc_login_request_ext() returned buffer Free it unconditionally after ksmbd_alloc_user() calls. kmemleak splat: unreferenced object 0xffff888103b83540 (size 192): comm "pool-0", pid 16970, jiffies 4377290937 hex dump (first 32 bytes): 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 408ccc66): __kvmalloc_node_noprof+0x730/0x920 handle_generic_event+0xec/0x1a0 [ksmbd] genl_family_rcv_msg_doit+0xe0/0x130 genl_rcv_msg+0x181/0x290 netlink_rcv_skb+0x4f/0x100 genl_rcv+0x28/0x40 netlink_unicast+0x1e6/0x2c0 netlink_sendmsg+0x20a/0x450 ____sys_sendmsg+0x2e8/0x310 ___sys_sendmsg+0x78/0xc0 __sys_sendmsg+0x63/0xc0 do_syscall_64+0xa1/0x670 entry_SYSCALL_64_after_hwframe+0x76/0x7e
02KernelScan AI Analysis
Risk summary
A memory leak in the kernel SMB server (ksmbd) authentication path allows a remote, unauthenticated attacker to exhaust kernel memory by repeatedly triggering SMB login attempts. Each authentication request leaks a small kernel buffer that is never freed, and sustained exploitation can drive the system to OOM or lockup. Any device running the ksmbd module with the SMB port exposed to a network is at risk.
Vulnerability analysis
When a client attempts to log in to the kernel SMB server (ksmbd), the server allocates a kernel buffer to hold supplementary group information for the user account. This buffer is then passed to the routine that creates the user session, but it is never freed afterward. The result is a small kernel memory leak on every authentication attempt. The fix ensures this buffer is released immediately after it is no longer needed, closing the leak in both the standard and Kerberos authentication paths. An attacker on the network can trigger this by repeatedly sending SMB authentication requests to any device with ksmbd loaded and reachable, with no credentials required.
Lifecycle
03Fix Versions
| Branch | Introduced | Fixed in | Patch commit |
|---|---|---|---|
| 6.6 | 6.6.141 | 6.6.157 | 4d6fe49fa3e7 |
| 6.12 | — | 6.12.110 | c9f2872e91b9 |
| 7.2 | — | 7.2.6 | abb5146b2d81 |
| mainline | — | 7.3-rc1 | 1c3ebf832d01 |
| 6.18 | — | 6.18.52 | 7a98c3b903b1 |