{"id":"CVE-2026-68284","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-68284","summary":"bpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Fix cork use-after-free in tcp_bpf_sendmsg()\n\ntcp_bpf_sendmsg() keeps msg_tx across sk_stream_wait_memory(), which\ndrops and reacquires the socket lock.  Its error path tries to decide\nwhether msg_tx names the local temporary message by comparing it with\nthe current value of psock->cork.\n\nThis comparison is unsafe when two threads send on the same socket:\n\n  Thread A                         Thread B\n  msg_tx = psock->cork\n  sk_msg_alloc() fails\n  sk_stream_wait_memory()\n    releases the socket lock      acquires the socket lock\n                                  completes the cork\n                                  psock->cork = NULL\n                                  frees the cork\n    reacquires the socket lock\n  msg_tx != psock->cork\n  sk_msg_free(msg_tx)\n\nThe stale cork is therefore mistaken for the local temporary message\nand freed again.  KASAN reported:\n\n  BUG: KASAN: slab-use-after-free in sk_msg_free+0x49/0x50\n  Read of size 4 at addr ffff88810c908800 by task poc/90\n  Call Trace:\n   sk_msg_free+0x49/0x50\n   tcp_bpf_sendmsg+0x14f5/0x1cc0\n   __sys_sendto+0x32c/0x3a0\n   __x64_sys_sendto+0xdb/0x1b0\n  Allocated by task 89:\n   __kasan_kmalloc+0x8f/0xa0\n   tcp_bpf_sendmsg+0x16b3/0x1cc0\n  Freed by task 91:\n   __kasan_slab_free+0x43/0x70\n   kfree+0x131/0x3c0\n   tcp_bpf_sendmsg+0xec3/0x1cc0\n\nmsg_tx can only name the stack-local tmp or the shared cork. Check for\ntmp directly so a changed psock->cork cannot turn a shared message into\nan apparent local one.","published":"2026-08-10T12:02:16.572Z","modified":"2026-08-14T04:03:56.474122138Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.6.148"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2d66a033864e27ab8d5e44cb36f31d9d2413bee4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/752b1159ed5d0c48fe169a3721b96660a9822aa1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/786d690257ec7a0c839f8710456e444ce3f1348b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cde4d6bcd9b73073c66498f6723c7b364c4dbc18"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ee762f684eefa59de34d9ed93cab08336e834f47"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68284.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68284"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-14T04:03:56.474122138Z"}}