{"id":"CVE-2026-43185","title":"ksmbd: fix signededness bug in smb_direct_prepare_negotiation()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix signededness bug in smb_direct_prepare_negotiation()\n\nsmb_direct_prepare_negotiation() casts an unsigned __u32 value\nfrom sp->max_recv_size and req->preferre…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 56eab82fa6fb5ca024b0514e249d40d9b23ee5a7","Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < a110dbe928561d440e9e117d17331139a0bedace","Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < ceae058eb707ddd0d68f0872f9d9f23b7c30c37b","Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 55abc475d096da4a5356b6efb0cfdc6156bc1550","Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 6b4f875aac344cdd52a1f34cc70ed2f874a65757","Linux 5.15"],"published":"2026-05-06","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:40:13.282Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43185","references":[{"url":"https://git.kernel.org/stable/c/56eab82fa6fb5ca024b0514e249d40d9b23ee5a7"},{"url":"https://git.kernel.org/stable/c/a110dbe928561d440e9e117d17331139a0bedace"},{"url":"https://git.kernel.org/stable/c/ceae058eb707ddd0d68f0872f9d9f23b7c30c37b"},{"url":"https://git.kernel.org/stable/c/55abc475d096da4a5356b6efb0cfdc6156bc1550"},{"url":"https://git.kernel.org/stable/c/6b4f875aac344cdd52a1f34cc70ed2f874a65757"}],"tags":["cve.org"],"epss":0.00702,"epssPercentile":0.52444,"ingestedAt":"2026-10-21T12:48:53.646Z","slug":"CVE-2026-43185","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix signededness bug in smb_direct_prepare_negotiation()\n\nsmb_direct_prepare_negotiation() casts an unsigned __u32 value\nfrom sp->max_recv_size and req->preferred_send_size to a signed\nint before computing min_t(int, ...). A maliciously provided\npreferred_send_size of 0x80000000 will return as smaller than\nmax_recv_size, and then be used to set the maximum allowed\nalowed receive size for the next message.\n\nBy sending a second message with a large value (>1420 bytes)\nthe attacker can then achieve a heap buffer overflow.\n\nThis fix replaces min_t(int, ...) with min_t(u32)\n\n## Affected\n\n- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 56eab82fa6fb5ca024b0514e249d40d9b23ee5a7`\n- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < a110dbe928561d440e9e117d17331139a0bedace`\n- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < ceae058eb707ddd0d68f0872f9d9f23b7c30c37b`\n- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 55abc475d096da4a5356b6efb0cfdc6156bc1550`\n- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 6b4f875aac344cdd52a1f34cc70ed2f874a65757`\n- `Linux 5.15`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}