CVE-2025-40363
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.
Affected versions
Linux kernel versions
2.6.12
and later are affected. Fixed in
5.4.302,
5.10.247,
5.15.197,
6.1.159,
6.6.117,
6.12.58,
6.17.8,
6.18
and their respective stable series.
References
The following references provide additional information about CVE-2025-40363 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
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PatchKernel patch commithttps://git.kernel.org/stable/c/0bf756ae1e69fec5e6332c37830488315d6d771b
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PatchKernel patch commithttps://git.kernel.org/stable/c/2327a3d6f65ce2fe2634546dde4a25ef52296fec
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PatchKernel patch commithttps://git.kernel.org/stable/c/2da805a61ef5272a2773775ce14c3650adb84248
Frequently asked questions
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What is CVE-2025-40363?
CVE-2025-40363 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 2.6.12 onward and has been patched in 5.4.302, 5.10.247, 5.15.197 and others. CVE-2025-40363 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2025-40363?
Yes — CVE-2025-40363 has been patched. Fixed versions include 5.4.302, 5.10.247, 5.15.197 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2025-40363 actively exploited?
No — CVE-2025-40363 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.