CVE-2025-40043 Affecting linux-6.1 package, versions <6.1.158-1~deb11u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.06% (18th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-14114861
  • published26 Nov 2025
  • disclosed28 Oct 2025

Introduced: 28 Oct 2025

CVE-2025-40043  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.158-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

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-&gt;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).

CVSS Base Scores

version 3.1