netfilter: ipset: fix refcount race between list:set GC and swap
In 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 exc
CVE-2026-74748
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-74748
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "97a01de0c6321b7210d30d0a4d60f10f561097c7",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "c21afc7c216a4d257a4f3f300e0791890bc846b9",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "b0aab9dd1a348b99d75ff52765719d0cc2050630",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "b891e7a6bb06e0f6560e5932665ac660acd12225",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "20cb13a523f0a05cb2d0a7d72abae687683712e0",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "cb20da33839f28f590c99f16bafaa6151451c0e8",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "24ffcb1e1688c55fd2a505f064295cd28eac546d",
"versionType": "git"
},
{
"status": "affected",
"version": "9076aea76538556224e7d73ab718f8841330818a",
"lessThan": "0c88868271653537ed443272dd8e7d13634d214b",
"versionType": "git"
}
],
"programFiles": [
"net/netfilter/ipset/ip_set_core.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.266",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.217",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.184",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.153",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.105",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/netfilter/ipset/ip_set_core.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-74748
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #34308 · Revision 1
- Added to Heist Feed
- Publisher date