Linux Kernel up to 6.17.2 nic_valid_size uninitialized pointer

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5.3$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 5.15.194/6.1.155/6.6.111/6.12.52/6.17.2. Affected by this issue is the function nic_valid_size. Performing a manipulation results in uninitialized pointer. This vulnerability was named CVE-2025-40043. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.15.194/6.1.155/6.6.111/6.12.52/6.17.2. It has been classified as critical. This affects the function nic_valid_size. The manipulation with an unknown input leads to a uninitialized pointer vulnerability. CWE is classifying the issue as CWE-824. The product accesses or uses a pointer that has not been initialized. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net: nfc: nci: Add parameter validation for packet data Syzbot reported an uninitialized value bug in nci_init_req, which was introduced by commit 5aca7966d2a7 ("Merge tag 'perf-tools-fixes-for-v6.17-2025-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools"). This bug arises due to very limited and poor input validation that was done at nic_valid_size(). This validation only validates the skb->len (directly reflects size provided at the userspace interface) with the length provided in the buffer itself (interpreted as NCI_HEADER). This leads to the processing of memory content at the address assuming the correct layout per what opcode requires there. This leads to the accesses to buffer of `skb_buff->data` which is not assigned anything yet. Following the same silent drop of packets of invalid sizes at `nic_valid_size()`, add validation of the data in the respective handlers and return error values in case of failure. Release the skb if error values are returned from handlers in `nci_nft_packet` and effectively do a silent drop Possible TODO: because we silently drop the packets, the call to `nci_request` will be waiting for completion of request and will face timeouts. These timeouts can get excessively logged in the dmesg. A proper handling of them may require to export `nci_request_cancel` (or propagate error handling from the nft packets handlers).

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-40043 since 04/16/2025. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 271887 (Linux Distros Unpatched Vulnerability : CVE-2025-40043), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.195, 6.1.156, 6.6.112, 6.12.53, 6.17.3 or 6.18-rc1 eliminates this vulnerability. Applying the patch 8fcc7315a10a84264e55bb65ede10f0af20a983f/bfdda0123dde406dbff62e7e9136037e97998a15/0ba68bea1e356f466ad29449938bea12f5f3711f/74837bca0748763a77f77db47a0bdbe63b347628/c395d1e548cc68e84584ffa2e3ca9796a78bf7b9/9c328f54741bd5465ca1dc717c84c04242fac2e1 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (271887) and CERT Bund (WID-SEC-2025-2431). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • IBM QRadar SIEM
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Microsoft Azure
  • Dell NetWorker
  • Dell ECS

Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Uninitialized pointer
CWE: CWE-824 / CWE-908
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 271887
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-40043

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.195/6.1.156/6.6.112/6.12.53/6.17.3/6.18-rc1
Patch: 8fcc7315a10a84264e55bb65ede10f0af20a983f/bfdda0123dde406dbff62e7e9136037e97998a15/0ba68bea1e356f466ad29449938bea12f5f3711f/74837bca0748763a77f77db47a0bdbe63b347628/c395d1e548cc68e84584ffa2e3ca9796a78bf7b9/9c328f54741bd5465ca1dc717c84c04242fac2e1

Timelineinfo

04/16/2025 CVE reserved
10/28/2025 +195 days Advisory disclosed
10/28/2025 +0 days VulDB entry created
05/19/2026 +203 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40043 (🔒)
GCVE (CVE): GCVE-0-2025-40043
GCVE (VulDB): GCVE-100-330243
CERT Bund: WID-SEC-2025-2431 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 10/28/2025 14:33
Updated: 05/19/2026 20:38
Changes: 10/28/2025 14:33 (18), 10/28/2025 14:34 (40), 10/29/2025 11:55 (2), 10/30/2025 03:40 (7), 10/30/2025 13:29 (1), 11/24/2025 13:18 (1), 12/22/2025 00:54 (1), 02/08/2026 16:45 (1), 02/15/2026 19:08 (1), 05/19/2026 20:38 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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