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Linux Kernel CVE-2026-72436

| EUVDEUVD-2026-59335 CRITICAL
2026-08-15 Linux GHSA-6x4x-6p4p-6f5f
Information Disclosure Linux Red Hat Suse
Critical
Disputed · 9.8 Vendor: Linux
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Severity by source

Sources disagree (Medium–Critical)
Vendor (Linux) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
3.6 LOW

Requires local CAP_NET_ADMIN to mutate ipsets (PR:L, AV:L) and winning a narrow race window (AC:H); realistic impact is limited info leak or filter inconsistency (C:L/A:L, I:N).

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L
4.0 AV:L/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
SUSE
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat
7.0 MEDIUM
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: Linux

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Generated
Aug 17, 2026 - 09:24 vuln.today
CVSS changed
Aug 17, 2026 - 06:22 NVD
9.8 (CRITICAL)
Patch available
Aug 15, 2026 - 07:20 EUVD
CVE Published
Aug 15, 2026 - 05:56 cve.org
CRITICAL 9.8
CVE Published
Aug 15, 2026 - 05:56 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types

Sashiko pointed out that there are a few lockless RCU readers using test_bit() which is a relaxed atomic operation and provides no memory barrier guarantees. Use test_bit_acquire() instead where the operation may run parallel with add/del/gc, i.e. is not one from the next cases

  • protected by region lock
  • in a set destroy phase
  • in a new/temporary set creation phase

AnalysisAI

Improper memory-barrier handling in the Linux kernel's netfilter ipset subsystem affects hash-type sets, where lockless RCU readers used the relaxed test_bit() operation instead of test_bit_acquire(), allowing readers running concurrently with add/delete/garbage-collection to observe stale or improperly ordered bit state. The flaw was fixed upstream and backported to stable trees; there is no public exploit identified at time of analysis and it is not in CISA KEV, and the EPSS score is very low (0.21%). Despite an automated NVD CVSS of 9.8, the defect is a memory-ordering race in a kernel packet-filtering path rather than a straightforward remote code execution primitive.

Technical ContextAI

The affected component is ipset, the Linux kernel netfilter feature that stores IP addresses, networks, ports and MACs in hash-based data structures (hash:* set types) for efficient firewall matching. ipset lookups occur in the packet-processing fast path under RCU (Read-Copy-Update), a lockless synchronization scheme where readers must use acquire-semantics primitives to correctly observe writes published by updaters. The bug is a missing-memory-barrier / data-race class issue (functionally CWE-362/CWE-366 territory; the input lists CWE as N/A): readers used test_bit(), a relaxed atomic with no ordering guarantees, so on weakly-ordered architectures a reader could see a bit value without the corresponding memory ordering versus a parallel add/del/gc operation. The fix substitutes test_bit_acquire() only in the reader paths that genuinely race with mutation, deliberately leaving paths protected by the region lock, or running during set destroy or new/temporary set creation, unchanged. The CPE data identifies the affected product generically as cpe:2.3:a:linux:linux, i.e. the mainline kernel.

RemediationAI

Vendor-released patch: upgrade to a fixed stable kernel - 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5, or 7.2-rc1 (or later on your branch), which is the primary and complete fix; in practice apply your Linux distribution's updated kernel package rather than building from the individual git.kernel.org/stable commits (c107233d, 6329d3a9, 7445fe96, c4d25773, 3219d74e, e4b4984e). If you cannot reboot into a patched kernel immediately, the practical compensating control is to restrict who can manipulate ipsets: avoid granting CAP_NET_ADMIN to untrusted users or containers, disable or restrict unprivileged user namespaces (sysctl kernel.unprivileged_userns_clone=0 where supported) so unprivileged processes cannot create their own netfilter/ipset contexts, and unload the ip_set modules on hosts that do not use ipset (modprobe -r ip_set and blacklist it) - the trade-off being that any firewall ruleset depending on ipset will stop functioning. These controls reduce the local attack surface but do not fix the underlying race, so patching remains the real remedy. Track the advisory at https://nvd.nist.gov/vuln/detail/CVE-2026-72436.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 16.0 Affected

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CVE-2026-72436 vulnerability details – vuln.today
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