GHSA-C7FW-HQHX-FX7Q
Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-19 18:32In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Reject unhashed UDP sockets on sockmap update
UDP sockets get SOCK_RCU_FREE set when (auto-)bound. This means sk_is_refcounted(unbound) = true, while sk_is_refcounted(bound) = false.
Because sockmap accepts unbound UDP sockets, a BPF program can increment a socket's refcount via lookup. If the socket is subsequently bound, the transition from unbound to bound causes bpf_sk_release() to skip the decrement of the refcount, causing a memory leak.
unreferenced object 0xffff88810bc2eb40 (size 1984): comm "test_progs", pid 2451, jiffies 4295320596 hex dump (first 32 bytes): 7f 00 00 01 7f 00 00 01 d2 04 1b b7 04 d2 00 00 ................ 02 00 01 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace (crc bdee079d): kmem_cache_alloc_noprof+0x557/0x660 sk_prot_alloc+0x69/0x240 sk_alloc+0x30/0x460 inet_create+0x2ce/0xf80 __sock_create+0x25b/0x5c0 __sys_socket+0x119/0x1d0 __x64_sys_socket+0x72/0xd0 do_syscall_64+0xa1/0x5f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Instead of special-casing for refcounted sockets, reject unhashed UDP sockets during sockmap updates, as there is no benefit to supporting those. This effectively reverts the commit under Fixes, with two exceptions:
- sock_map_sk_state_allowed() maintains a fall-through
return true. - In the spirit of commit b8b8315e39ff ("bpf, sockmap: Remove unhash handler for BPF sockmap usage"), the proto::unhash BPF handler is not reintroduced.
Historical note: this issue is related to commit 67312adc96b5 ("bpf: reject unhashed sockets in bpf_sk_assign").
{
"affected": [],
"aliases": [
"CVE-2026-68386"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-10T13:20:31Z",
"severity": null
},
"details": "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_is_refcounted(bound) = false.\n\nBecause sockmap accepts unbound UDP sockets, a BPF program can increment a\nsocket\u0027s 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\").",
"id": "GHSA-c7fw-hqhx-fx7q",
"modified": "2026-08-19T18:32:17Z",
"published": "2026-08-10T15:33:49Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68386"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/17b7ef6b86112a4e61cee1e9009a4b318e3225c5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2271276ac5279d2d204be7739a1a28d4ef6cf608"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/250474c69bc3fc48a5fc21d7c349f279caad947a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/66efd3368ae10d05e08fbe6425b50fdec7186ac7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7ffe529e7127411806c8692fb1490f552c629dc2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8692655da369961128658cf8539334b6a960ecb0"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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