{"id":"CVE-2026-68386","title":"bpf, sockmap: Reject unhashed UDP sockets on sockmap update","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Reject unhashed UDP sockets on sockmap update\n\nUDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means\nsk_is_refcounted(unbound) = true, while sk_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 2271276ac5279d2d204be7739a1a28d4ef6cf608","Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 7ffe529e7127411806c8692fb1490f552c629dc2","Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 17b7ef6b86112a4e61cee1e9009a4b318e3225c5","Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 250474c69bc3fc48a5fc21d7c349f279caad947a","Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 8692655da369961128658cf8539334b6a960ecb0","Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 66efd3368ae10d05e08fbe6425b50fdec7186ac7","Linux 5.15"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:48:28.442498Z"},"published":"2026-08-10","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:55:15.101Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68386","references":[{"url":"https://git.kernel.org/stable/c/2271276ac5279d2d204be7739a1a28d4ef6cf608"},{"url":"https://git.kernel.org/stable/c/7ffe529e7127411806c8692fb1490f552c629dc2"},{"url":"https://git.kernel.org/stable/c/17b7ef6b86112a4e61cee1e9009a4b318e3225c5"},{"url":"https://git.kernel.org/stable/c/250474c69bc3fc48a5fc21d7c349f279caad947a"},{"url":"https://git.kernel.org/stable/c/8692655da369961128658cf8539334b6a960ecb0"},{"url":"https://git.kernel.org/stable/c/66efd3368ae10d05e08fbe6425b50fdec7186ac7"}],"tags":["cve.org"],"epss":0.00211,"epssPercentile":0.11442,"ingestedAt":"2026-11-06T18:00:12.606Z","slug":"CVE-2026-68386","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Reject unhashed UDP sockets on sockmap update\n\nUDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means\nsk_is_refcounted(unbound) = true, while sk_is_refcounted(bound) = false.\n\nBecause sockmap accepts unbound UDP sockets, a BPF program can increment a\nsocket's refcount via lookup. If the socket is subsequently bound, the\ntransition from unbound to bound causes bpf_sk_release() to skip the\ndecrement of the refcount, causing a memory leak.\n\nunreferenced object 0xffff88810bc2eb40 (size 1984):\n  comm \"test_progs\", pid 2451, jiffies 4295320596\n  hex dump (first 32 bytes):\n    7f 00 00 01 7f 00 00 01 d2 04 1b b7 04 d2 00 00  ................\n    02 00 01 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............\n  backtrace (crc bdee079d):\n    kmem_cache_alloc_noprof+0x557/0x660\n    sk_prot_alloc+0x69/0x240\n    sk_alloc+0x30/0x460\n    inet_create+0x2ce/0xf80\n    __sock_create+0x25b/0x5c0\n    __sys_socket+0x119/0x1d0\n    __x64_sys_socket+0x72/0xd0\n    do_syscall_64+0xa1/0x5f0\n    entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nInstead of special-casing for refcounted sockets, reject unhashed UDP\nsockets during sockmap updates, as there is no benefit to supporting those.\nThis effectively reverts the commit under Fixes, with two exceptions:\n\n1. sock_map_sk_state_allowed() maintains a fall-through `return true`.\n2. In the spirit of commit b8b8315e39ff (\"bpf, sockmap: Remove unhash\n   handler for BPF sockmap usage\"), the proto::unhash BPF handler is not\n   reintroduced.\n\nHistorical note: this issue is related to commit 67312adc96b5 (\"bpf: reject\nunhashed sockets in bpf_sk_assign\").\n\n## Affected\n\n- `Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 2271276ac5279d2d204be7739a1a28d4ef6cf608`\n- `Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 7ffe529e7127411806c8692fb1490f552c629dc2`\n- `Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 17b7ef6b86112a4e61cee1e9009a4b318e3225c5`\n- `Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 250474c69bc3fc48a5fc21d7c349f279caad947a`\n- `Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 8692655da369961128658cf8539334b6a960ecb0`\n- `Linux >= 0c48eefae712c2fd91480346a07a1a9cd0f9470b < 66efd3368ae10d05e08fbe6425b50fdec7186ac7`\n- `Linux 5.15`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}