CVE-2025-40363
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-16

Last updated on: 2025-12-18

Assigner: kernel.org

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.
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Meta Information
Published
2025-12-16
Last Modified
2025-12-18
Generated
2026-06-16
AI Q&A
2025-12-16
EPSS Evaluated
2026-06-15
NVD
CVE-2025-40363
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability involves a false positive warning in the Linux kernel's IPv6 implementation, specifically in the ah6_output() and ah6_output_done() functions. The issue is related to memcpy operations that span fields when copying extension headers to or from IPv6 address fields, triggering fortify-string warnings about writes beyond the 16-byte IPv6 address fields. The warnings occur because extension headers are intentionally placed after the IPv6 header in memory. The fix involves properly copying addresses and extension headers separately and introducing helper functions to avoid code duplication.

Impact Analysis

This vulnerability does not represent an actual security flaw but rather a false positive warning during memory copying operations in the Linux kernel's IPv6 code. Therefore, it is unlikely to have a direct impact on system security or stability. The fix improves code correctness and avoids misleading compiler warnings.

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