[CVE-2024-53141][IMPORTANT] netfilter: ipset: add missing range check in bitmap_ip_uadt

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2024-53141
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: netfilter: ipset: add missing range check in bitmap_ip_uadt
Commit: 3c20b5948f119ae61ee35ad8584d666020c91581
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c20b5948f119ae61ee35ad8584d666020c91581
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2024-53141
Analysis date: Mon, 12 Oct 2026 20:22:10 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2024-53141 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2024-53141

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: IMPORTANT
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2024-53141	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2024-53141 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=2 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (independent Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-125;CWE-129;*CWE-20;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'A missing lower bound check in bitmap_ip_uadt can accept an IP address below map first_ip when CIDR based range processing is used. Converting that address into a bitmap identifier can underflow the unsigned subtraction and produce an index outside the allocated members bitmap. Test operations may read outside the bitmap while add or delete operations may perform an out-of-bounds bit modification, causing kernel memory corruption or a kernel crash. For the CVSS the PR:L reflects that the attacker needs local access to the ipset Netlink control interface and normally CAP_NET_ADMIN, which may be available to a container root or a process with delegated network administration capability without full host root access. The issue is not directly reachable through ordinary network packets. Impact is at least a local denial of service and the out-of-bounds bitmap modification creates a plausible privilege escalation risk that should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)	MAYBE	REMOTE DANGER SIMPLEFIX NETFILTER LINUS SYZBOT TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=5
PrimitiveClass=CLASS_A
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=YES
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw conservative score: 4.
* Conservative score: 5. The manual-review safety floor for a concrete attacker-influenced kernel OOB write changes 4 to 5.
* Raw paranoid score: 4.
* Paranoid score: 5. No additional speculative exploitation points were added. The same strong-corruption safety floor changes 4 to 5.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 Strong corruption primitive. An address below `map->first_ip` can reach bitmap index calculation, where unsigned subtraction can produce an index outside the allocated members bitmap. Add and delete operations subsequently perform an attacker-influenced bit write at that invalid index.
* +1 Local unprivileged trigger. The ipset nfnetlink control path is governed by network-namespace `CAP_NET_ADMIN`. Where unprivileged user and network namespace creation is enabled, an ordinary user can obtain that capability for an owned network namespace and exercise the complete namespace-local operation.
* +1 Reliable kernel crash or strong DoS. An out-of-bounds bitmap bit operation can access unmapped or unrelated kernel memory and can realistically produce an Oops or panic.
* +0 No privilege penalty. Host-admin-equivalent authority is not required for the namespace-local path.
* +0 No race penalty. The defect is a deterministic validation and index-calculation error, not a timing race.
* +0 No additional integrity point. Although an actual kernel write occurs, no adjacent victim object or protected state modification is demonstrated.
* +0 No strong LPE leverage point. Controlled target selection, arbitrary payload, controlled reclaim, credential corruption, and a completed privilege-escalation chain are not established.
* +0 No remote-reachability point. Ordinary network packets do not directly invoke this ipset control-plane operation.
* +0 No extra availability point. The possible kernel crash is counted once.
* +0 NEW52 B5-R does not apply. No retry-accumulated index, missing retry reset, or later consumption of retry-corrupted descriptor state is present.
* +0 NEW53 B3-PENDING does not apply. This is not a shared-backing or file-backed page write.
* +0 NEW54 B4-PENDING does not apply. No authorization decision changes from DENY to ALLOW.

3. Reachability analysis

The trigger is a local nfnetlink ipset operation using the `bitmap:ip` set type and a CIDR-derived range whose lower endpoint falls below `first_ip`. The operation normally requires `CAP_NET_ADMIN`, but the relevant netfilter and ipset objects are network-namespace scoped, and the capability check is evaluated against the network namespace authority.

On systems permitting unprivileged user and network namespace creation, an ordinary user can create an owned namespace, obtain namespace-local `CAP_NET_ADMIN`, instantiate the ipset object, and submit the malformed update. A delegated container or network-management service can exercise the same path without host-administrator authority. No numeric host UID 0 requirement is inherent to this model.

`CONFIG_IP_SET` and the bitmap IP set type must be available, but no special hardware, boot mode, race, or separate privileged host-created topology is required. The issue is not directly network-triggerable through packet traffic.

4. Primitive and severity interpretation

The primitive is an attacker-influenced heap or slab out-of-bounds bit write. The missing lower-bound check permits `ip < map->first_ip`. The subsequent unsigned IP-to-bitmap-index calculation can underflow, and bitmap add or delete operations can set or clear a bit outside the allocated members array. A test operation can instead perform an out-of-bounds read.

This is not a UAF, stale-storage issue, cleanup bug, repeated release, or authorization bypass. It is CLASS_A because an actual attacker-influenced OOB write follows from the range/index mismatch. The write remains constrained to a bit operation and the available evidence does not establish an arbitrary address, arbitrary value, selected adjacent victim, disclosure, or privilege escalation.

The demonstrated practical consequences are kernel memory corruption and possible host crash. Privilege escalation is technically plausible enough to require manual layout and reachability analysis, but it is not demonstrated. `ImportantCandidate=YES` and `AutoDowngradeAllowed=NO` preserve the concrete write primitive without claiming proven Important-grade impact.

5. One-sentence report phrase

A namespace-capable local attacker can supply a CIDR-derived IP below the bitmap range and trigger an out-of-bounds kernel bitmap bit operation, causing memory corruption or a kernel crash and requiring manual exploitation review.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Confirm the exact index width and wrap behavior, reachable add and delete operations, maximum controllable offset, allocator placement, adjacent object classes, and whether the bit set or clear primitive can modify security-sensitive kernel state.

7. Call-site confidence

Call-site confidence: medium

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: netfilter: ipset: add missing range check in bitmap_ip_uadt
Commit: 3c20b5948f119ae61ee35ad8584d666020c91581
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c20b5948f119ae61ee35ad8584d666020c91581

Commit description:

When tb[IPSET_ATTR_IP_TO] is not present but tb[IPSET_ATTR_CIDR] exists,
the values of ip and ip_to are slightly swapped. Therefore, the range check
for ip should be done later, but this part is missing and it seems that the
vulnerability occurs.

So we should add missing range checks and remove unnecessary range checks.

Cc: <stable@vger.kernel.org>
Reported-by: syzbot+58c872f7790a4d2ac951@syzkaller.appspotmail.com
Fixes: 72205fc ("netfilter: ipset: bitmap:ip set type support")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/netfilter/ipset/ip_set_bitmap_ip.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c20b5948f119ae61ee35ad8584d666020c91581

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2024-53141 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2024-53141

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: unknown
  Paranoid ActionableScore: 5

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: IMPORTANT
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): IMPORTANT

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).