CVE-2025-40363

net: ipv6: fix field-spanning memcpy warning in AH output

State: Published
Severity: Not scored
Published: Dec 16, 2025
Updated: Jun 16, 2026
Reserved: Apr 16, 2025

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 2da805a61ef5272a2773775ce14c3650adb84248Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 9bf27de51bd6db5ff827780ec0eba55de230ba45Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 0bf756ae1e69fec5e6332c37830488315d6d771bAffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 75b16b2755e12999ad850756ddfb88ad4bfc7186Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before f28dde240160f3c48a50d641d210ed6a3b9596edAffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before c14cf41094136691c92ef756872570645d61f4a1Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before b056f971bd72b373b7ae2025a8f3bd18f69653d3Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 2327a3d6f65ce2fe2634546dde4a25ef52296fecAffected
LinuxLinux	2.6.12Affected before 2.6.12Not affected 5.4.302 through 5.4.Not affected 5.10.247 through 5.10.Not affected 5.15.197 through 5.15.Not affected 6.1.159 through 6.1.Not affected 6.6.117 through 6.6.Not affected 6.12.58 through 6.12.Not affected 6.17.8 through 6.17.*Not affected 6.18 and laterNot affected

Product

Versions

LinuxLinux

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 2da805a61ef5272a2773775ce14c3650adb84248Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 9bf27de51bd6db5ff827780ec0eba55de230ba45Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 0bf756ae1e69fec5e6332c37830488315d6d771bAffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 75b16b2755e12999ad850756ddfb88ad4bfc7186Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before f28dde240160f3c48a50d641d210ed6a3b9596edAffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before c14cf41094136691c92ef756872570645d61f4a1Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before b056f971bd72b373b7ae2025a8f3bd18f69653d3Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 2327a3d6f65ce2fe2634546dde4a25ef52296fecAffected

LinuxLinux

2.6.12Affected
before 2.6.12Not affected
5.4.302 through 5.4.*Not affected
5.10.247 through 5.10.*Not affected
5.15.197 through 5.15.*Not affected
6.1.159 through 6.1.*Not affected
6.6.117 through 6.6.*Not affected
6.12.58 through 6.12.*Not affected
6.17.8 through 6.17.*Not affected
6.18 and laterNot affected

References

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