cbcvebase.
CVE-2026-22977
published 2026-01-21

CVE-2026-22977: In the Linux kernel, the following vulnerability has been resolved: net: sock: fix hardened usercopy panic in sock_recv_errqueue skbuff_fclone_cache was…

PriorityP422medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.13%
2.7th percentile
In the Linux kernel, the following vulnerability has been resolved: net: sock: fix hardened usercopy panic in sock_recv_errqueue skbuff_fclone_cache was created without defining a usercopy region, [1] unlike skbuff_head_cache which properly whitelists the cb[] field. [2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is enabled and the kernel attempts to copy sk_buff.cb data to userspace via sock_recv_errqueue() -> put_cmsg(). The crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone() (from skbuff_fclone_cache) [1] 2. The skb is cloned via skb_clone() using the pre-allocated fclone [3] 3. The cloned skb is queued to sk_error_queue for timestamp reporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE) 5. sock_recv_errqueue() calls put_cmsg() to copy serr->ee from skb->cb [4] 6. __check_heap_object() fails because skbuff_fclone_cache has no usercopy whitelist [5] When cloned skbs allocated from skbuff_fclone_cache are used in the socket error queue, accessing the sock_exterr_skb structure in skb->cb via put_cmsg() triggers a usercopy hardening violation: [ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (offset 296, size 16)! [ 5.382796] kernel BUG at mm/usercopy.c:102! [ 5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI [ 5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7 [ 5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 5.384903] RIP: 0010:usercopy_abort+0x6c/0x80 [ 5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff 0b 490 [ 5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246 [ 5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74 [ 5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0 [ 5.384903] RBP: 0000000000000010 R08: 0000

Affected

56 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.162-1 (bookworm)linux 6.1.162-1 (bookworm)
debianlinux-6.1< linux 6.1.162-1 (bookworm)linux 6.1.162-1 (bookworm)
linuxlinux
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < 88dd6be7ebb3153b662c2cebcb06e032a92857f588dd6be7ebb3153b662c2cebcb06e032a92857f5
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < c655d2167bf014d4c61b4faeca59b60ff9b9f6b1c655d2167bf014d4c61b4faeca59b60ff9b9f6b1
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < 8c6901aa29626e35045130bac09b75f791acca858c6901aa29626e35045130bac09b75f791acca85
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < 582a5e922a9652fcbb7d0165c95d5b20aa37575d582a5e922a9652fcbb7d0165c95d5b20aa37575d
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < 005671c60fcf1dbdb8bddf12a62568fd5e4ec391005671c60fcf1dbdb8bddf12a62568fd5e4ec391
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < e00b169eaac5f7cdbf710c354c8fa76d02009115e00b169eaac5f7cdbf710c354c8fa76d02009115
linuxlinux>= 6d07d1cd300f4c7e16005f881fea388164999cc8 < 2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae202a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 5.10.249-15.10.249-1
linuxlinux_kernel>= 0 < 6.1.162-16.1.162-1
linuxlinux_kernel>= 0 < 6.12.69-16.12.69-1
linuxlinux_kernel>= 0 < 6.18.8-16.18.8-1
linuxlinux_kernel>= 0 < 5.15.0-173.1835.15.0-173.183
linuxlinux_kernel>= 4.16 < 5.10.2485.10.248
linuxlinux_kernel>= 5.11 < 5.15.1985.15.198
linuxlinux_kernel>= 5.16 < 6.1.1616.1.161
linuxlinux_kernel>= 6.13 < 6.18.66.18.6
linuxlinux_kernel>= 6.2 < 6.6.1216.6.121
linuxlinux_kernel>= 6.7 < 6.12.666.12.66

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.8HIGH
vendor_ubuntu7.8HIGH
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
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