High

CVE-2026-74748 — 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: <IRQ> 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) </IRQ> Kernel panic - not syncing: Fatal exception in interrupt

Published Aug 26, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

—

No EPSS score.

Affects

Linux

CVSS base

7.8

High · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ 9076aea76538556224e7d73ab718f8841330818a and < 97a01de0c6321b7210d30d0a4d60f10f561097c7≥ 9076aea76538556224e7d73ab718f8841330818a and < c21afc7c216a4d257a4f3f300e0791890bc846b9≥ 9076aea76538556224e7d73ab718f8841330818a and < b0aab9dd1a348b99d75ff52765719d0cc2050630≥ 9076aea76538556224e7d73ab718f8841330818a and < b891e7a6bb06e0f6560e5932665ac660acd12225≥ 9076aea76538556224e7d73ab718f8841330818a and < 20cb13a523f0a05cb2d0a7d72abae687683712e0≥ 9076aea76538556224e7d73ab718f8841330818a and < cb20da33839f28f590c99f16bafaa6151451c0e8≥ 9076aea76538556224e7d73ab718f8841330818a and < 24ffcb1e1688c55fd2a505f064295cd28eac546d≥ 9076aea76538556224e7d73ab718f8841330818a and < 0c88868271653537ed443272dd8e7d13634d214b and 1 more version 3.8	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.8	CVSS 3.1	High	1.8	5.9	416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
7.8	CVSS 3.1	High	—	—	Linux via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.

endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 7.8
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 26, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

git.kernel.org/stable/c/cb20da33839f28f590c99f16bafaa6151451c0e8
NIST National Vulnerability Database
git.kernel.org/stable/c/20cb13a523f0a05cb2d0a7d72abae687683712e0
NIST National Vulnerability Database
git.kernel.org/stable/c/c21afc7c216a4d257a4f3f300e0791890bc846b9
NIST National Vulnerability Database
git.kernel.org/stable/c/97a01de0c6321b7210d30d0a4d60f10f561097c7
NIST National Vulnerability Database
git.kernel.org/stable/c/0c88868271653537ed443272dd8e7d13634d214b
NIST National Vulnerability Database
git.kernel.org/stable/c/b0aab9dd1a348b99d75ff52765719d0cc2050630
NIST National Vulnerability Database
git.kernel.org/stable/c/b891e7a6bb06e0f6560e5932665ac660acd12225
NIST National Vulnerability Database
git.kernel.org/stable/c/24ffcb1e1688c55fd2a505f064295cd28eac546d
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 13h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 13h
Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No FIRST EPSS score.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-74748 is "netfilter: ipset: fix refcount race between list:set GC and swap", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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