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.

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00024.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Linux
  • Linux Kernel

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References
Link Providers
https://git.kernel.org/stable/c/0bf756ae1e69fec5e6332c37830488315d6d771b cve-icon cve-icon
https://git.kernel.org/stable/c/2327a3d6f65ce2fe2634546dde4a25ef52296fec cve-icon cve-icon
https://git.kernel.org/stable/c/2da805a61ef5272a2773775ce14c3650adb84248 cve-icon cve-icon
https://git.kernel.org/stable/c/75b16b2755e12999ad850756ddfb88ad4bfc7186 cve-icon cve-icon
https://git.kernel.org/stable/c/9bf27de51bd6db5ff827780ec0eba55de230ba45 cve-icon cve-icon
https://git.kernel.org/stable/c/b056f971bd72b373b7ae2025a8f3bd18f69653d3 cve-icon cve-icon
https://git.kernel.org/stable/c/c14cf41094136691c92ef756872570645d61f4a1 cve-icon cve-icon
https://git.kernel.org/stable/c/f28dde240160f3c48a50d641d210ed6a3b9596ed cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2025121645-CVE-2025-40363-bbdd@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2025-40363 cve-icon
https://www.cve.org/CVERecord?id=CVE-2025-40363 cve-icon
History

Wed, 17 Dec 2025 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

Tue, 16 Dec 2025 14:00:00 +0000

Type Values Removed Values 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.
Title net: ipv6: fix field-spanning memcpy warning in AH output
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-12-16T13:40:03.265Z

Reserved: 2025-04-16T07:20:57.187Z

Link: CVE-2025-40363

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2025-12-16T14:15:48.327

Modified: 2025-12-16T14:15:48.327

Link: CVE-2025-40363

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-12-16T00:00:00Z

Links: CVE-2025-40363 - Bugzilla

cve-icon OpenCVE Enrichment

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