GHSA-HF83-XV8X-WGQ9
Vulnerability from github – Published: 2026-08-27 06:31 – Updated: 2026-08-27 06:31In the Linux kernel, the following vulnerability has been resolved:
netfilter: ipset: fix refcount race between list:set GC and swap
__ip_set_put_byindex() resolved the index to a set pointer under RCU, then took ip_set_ref_lock in __ip_set_put() to decrement set->ref. ip_set_swap() holds that same lock while swapping both the ip_set_list slots and the two sets' ref counters, so it can interleave between the dereference and the lock acquisition, leaving the caller to decrement a set whose reference already moved to the other index and hit BUG_ON(set->ref == 0). list_set_gc() reaches this from timer softirq, which the nfnl mutex does not serialize against swap: an expiring list:set member calls list_set_del() -> ip_set_put_byindex() while IPSET_CMD_SWAP runs on the referenced sets.
Resolve the index and decrement under ip_set_ref_lock, as ip_set_swap() already does, keeping the refcount tied to the index rather than to a stale set pointer.
kernel BUG at net/netfilter/ipset/ip_set_core.c:685! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ip_set_put_byindex (net/netfilter/ipset/ip_set_core.c:870) Call Trace: list_set_del (net/netfilter/ipset/ip_set_list_set.c:159) set_cleanup_entries (net/netfilter/ipset/ip_set_list_set.c:181) list_set_gc (net/netfilter/ipset/ip_set_list_set.c:578) call_timer_fn (kernel/time/timer.c:1748) __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2374) run_timer_softirq (kernel/time/timer.c:2405) Kernel panic - not syncing: Fatal exception in interrupt
{
"affected": [],
"aliases": [
"CVE-2026-74748"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-26T15:16:53Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ipset: fix refcount race between list:set GC and swap\n\n__ip_set_put_byindex() resolved the index to a set pointer under RCU,\nthen took ip_set_ref_lock in __ip_set_put() to decrement set-\u003eref.\nip_set_swap() holds that same lock while swapping both the ip_set_list\nslots and the two sets\u0027 ref counters, so it can interleave between the\ndereference and the lock acquisition, leaving the caller to decrement a\nset whose reference already moved to the other index and hit\nBUG_ON(set-\u003eref == 0). list_set_gc() reaches this from timer softirq,\nwhich the nfnl mutex does not serialize against swap: an expiring\nlist:set member calls list_set_del() -\u003e ip_set_put_byindex() while\nIPSET_CMD_SWAP runs on the referenced sets.\n\nResolve the index and decrement under ip_set_ref_lock, as ip_set_swap()\nalready does, keeping the refcount tied to the index rather than to a\nstale set pointer.\n\n kernel BUG at net/netfilter/ipset/ip_set_core.c:685!\n Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n RIP: 0010:ip_set_put_byindex (net/netfilter/ipset/ip_set_core.c:870)\n Call Trace:\n \u003cIRQ\u003e\n list_set_del (net/netfilter/ipset/ip_set_list_set.c:159)\n set_cleanup_entries (net/netfilter/ipset/ip_set_list_set.c:181)\n list_set_gc (net/netfilter/ipset/ip_set_list_set.c:578)\n call_timer_fn (kernel/time/timer.c:1748)\n __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2374)\n run_timer_softirq (kernel/time/timer.c:2405)\n \u003c/IRQ\u003e\n Kernel panic - not syncing: Fatal exception in interrupt",
"id": "GHSA-hf83-xv8x-wgq9",
"modified": "2026-08-27T06:31:31Z",
"published": "2026-08-27T06:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74748"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0c88868271653537ed443272dd8e7d13634d214b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/20cb13a523f0a05cb2d0a7d72abae687683712e0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/24ffcb1e1688c55fd2a505f064295cd28eac546d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/97a01de0c6321b7210d30d0a4d60f10f561097c7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b0aab9dd1a348b99d75ff52765719d0cc2050630"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b891e7a6bb06e0f6560e5932665ac660acd12225"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c21afc7c216a4d257a4f3f300e0791890bc846b9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cb20da33839f28f590c99f16bafaa6151451c0e8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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