{"id":"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-\u003ecork.\n\nThis comparison is unsafe when two threads send on the same socket:\n\n  Thread A                         Thread B\n  msg_tx = psock-\u003ecork\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-\u003ecork = NULL\n                                  frees the cork\n    reacquires the socket lock\n  msg_tx != psock-\u003ecork\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-\u003ecork cannot turn a shared message into\nan apparent local one.","modified":"2026-08-21T03:30:42.380407121Z","published":"2026-08-10T12:02:16.572Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68284.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0688e6fe599d2d39147ae9ece97944c6e1815ebf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2d66a033864e27ab8d5e44cb36f31d9d2413bee4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/54be47e7cbb936429c3bbdfc526ea943954aaf80"},{"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/b2bcbeabfd843d47468fa095b1bd08ddb90cf616"},{"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"604326b41a6fb9b4a78b6179335decee0365cd8c"},{"fixed":"0688e6fe599d2d39147ae9ece97944c6e1815ebf"},{"fixed":"b2bcbeabfd843d47468fa095b1bd08ddb90cf616"},{"fixed":"54be47e7cbb936429c3bbdfc526ea943954aaf80"},{"fixed":"ee762f684eefa59de34d9ed93cab08336e834f47"},{"fixed":"cde4d6bcd9b73073c66498f6723c7b364c4dbc18"},{"fixed":"786d690257ec7a0c839f8710456e444ce3f1348b"},{"fixed":"752b1159ed5d0c48fe169a3721b96660a9822aa1"},{"fixed":"2d66a033864e27ab8d5e44cb36f31d9d2413bee4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68284.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68284.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}