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CVE-2025-40363
net: ipv6: fix field-spanning memcpy warning in AH output
Description

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix field-spanning memcpy warning in AH output Fix field-spanning memcpy warnings in ah6_output() and ah6_output_done() where extension headers are copied to/from IPv6 address fields, triggering fortify-string warnings about writes beyond the 16-byte address fields. memcpy: detected field-spanning write (size 40) of single field "&top_iph->saddr" at net/ipv6/ah6.c:439 (size 16) WARNING: CPU: 0 PID: 8838 at net/ipv6/ah6.c:439 ah6_output+0xe7e/0x14e0 net/ipv6/ah6.c:439 The warnings are false positives as the extension headers are intentionally placed after the IPv6 header in memory. Fix by properly copying addresses and extension headers separately, and introduce helper functions to avoid code duplication.

INFO

Published Date :

Dec. 16, 2025, 2:15 p.m.

Last Modified :

Dec. 16, 2025, 2:15 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-40363 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Solution
Update the Linux kernel to fix a memcpy warning in IPv6 AH output.
  • Apply the patch for net: ipv6: fix field-spanning memcpy warning.
  • Update to a patched Linux kernel version.
  • Recompile and deploy the updated kernel.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-40363.

URL Resource
https://git.kernel.org/stable/c/0bf756ae1e69fec5e6332c37830488315d6d771b
https://git.kernel.org/stable/c/2327a3d6f65ce2fe2634546dde4a25ef52296fec
https://git.kernel.org/stable/c/2da805a61ef5272a2773775ce14c3650adb84248
https://git.kernel.org/stable/c/75b16b2755e12999ad850756ddfb88ad4bfc7186
https://git.kernel.org/stable/c/9bf27de51bd6db5ff827780ec0eba55de230ba45
https://git.kernel.org/stable/c/b056f971bd72b373b7ae2025a8f3bd18f69653d3
https://git.kernel.org/stable/c/c14cf41094136691c92ef756872570645d61f4a1
https://git.kernel.org/stable/c/f28dde240160f3c48a50d641d210ed6a3b9596ed
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-40363 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-40363 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-40363 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-40363 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Dec. 16, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix field-spanning memcpy warning in AH output Fix field-spanning memcpy warnings in ah6_output() and ah6_output_done() where extension headers are copied to/from IPv6 address fields, triggering fortify-string warnings about writes beyond the 16-byte address fields. memcpy: detected field-spanning write (size 40) of single field "&top_iph->saddr" at net/ipv6/ah6.c:439 (size 16) WARNING: CPU: 0 PID: 8838 at net/ipv6/ah6.c:439 ah6_output+0xe7e/0x14e0 net/ipv6/ah6.c:439 The warnings are false positives as the extension headers are intentionally placed after the IPv6 header in memory. Fix by properly copying addresses and extension headers separately, and introduce helper functions to avoid code duplication.
    Added Reference https://git.kernel.org/stable/c/0bf756ae1e69fec5e6332c37830488315d6d771b
    Added Reference https://git.kernel.org/stable/c/2327a3d6f65ce2fe2634546dde4a25ef52296fec
    Added Reference https://git.kernel.org/stable/c/2da805a61ef5272a2773775ce14c3650adb84248
    Added Reference https://git.kernel.org/stable/c/75b16b2755e12999ad850756ddfb88ad4bfc7186
    Added Reference https://git.kernel.org/stable/c/9bf27de51bd6db5ff827780ec0eba55de230ba45
    Added Reference https://git.kernel.org/stable/c/b056f971bd72b373b7ae2025a8f3bd18f69653d3
    Added Reference https://git.kernel.org/stable/c/c14cf41094136691c92ef756872570645d61f4a1
    Added Reference https://git.kernel.org/stable/c/f28dde240160f3c48a50d641d210ed6a3b9596ed
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.