{"id":"CVE-2026-23243","title":"RDMA/umad: Reject negative data_len in ib_umad_write","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/umad: Reject negative data_len in ib_umad_write\n\nib_umad_write computes data_len from user-controlled count and the\nMAD header sizes. With a mismatched user MAD he…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 1371ef6b1ecf3676b8942f5dfb3634fb0648128e","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 362e45fd9069ffa1523f9f1633b606ebf72060d7","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 6eb2919474ca105c5b13d19574e25f0ddcf19ca2","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 9c80d688f402539dfc8f336de1380d6b4ee14316","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 205955f29c26330b1dc7fdeadd5bb97c38e26f56","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 52ab82cc5cf8ada5c3fb6ffe8f32fdb2fc27a34b","Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 5551b02fdbfd85a325bb857f3a8f9c9f33397ed2","Linux 2.6.24"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-06-17T17:47:24.163717Z"},"published":"2026-03-18","updated":"2026-09-08","sourceUpdated":"2026-09-08T08:45:08.401Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23243","references":[{"url":"https://git.kernel.org/stable/c/1371ef6b1ecf3676b8942f5dfb3634fb0648128e"},{"url":"https://git.kernel.org/stable/c/362e45fd9069ffa1523f9f1633b606ebf72060d7"},{"url":"https://git.kernel.org/stable/c/6eb2919474ca105c5b13d19574e25f0ddcf19ca2"},{"url":"https://git.kernel.org/stable/c/a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d"},{"url":"https://git.kernel.org/stable/c/9c80d688f402539dfc8f336de1380d6b4ee14316"},{"url":"https://git.kernel.org/stable/c/205955f29c26330b1dc7fdeadd5bb97c38e26f56"},{"url":"https://git.kernel.org/stable/c/52ab82cc5cf8ada5c3fb6ffe8f32fdb2fc27a34b"},{"url":"https://git.kernel.org/stable/c/5551b02fdbfd85a325bb857f3a8f9c9f33397ed2"}],"tags":["cve.org"],"epss":0.00131,"epssPercentile":0.03037,"ingestedAt":"2026-09-08T15:33:26.993Z","slug":"CVE-2026-23243","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/umad: Reject negative data_len in ib_umad_write\n\nib_umad_write computes data_len from user-controlled count and the\nMAD header sizes. With a mismatched user MAD header size and RMPP\nheader length, data_len can become negative and reach ib_create_send_mad().\nThis can make the padding calculation exceed the segment size and trigger\nan out-of-bounds memset in alloc_send_rmpp_list().\n\nAdd an explicit check to reject negative data_len before creating the\nsend buffer.\n\nKASAN splat:\n[  211.363464] BUG: KASAN: slab-out-of-bounds in ib_create_send_mad+0xa01/0x11b0\n[  211.364077] Write of size 220 at addr ffff88800c3fa1f8 by task spray_thread/102\n[  211.365867] ib_create_send_mad+0xa01/0x11b0\n[  211.365887] ib_umad_write+0x853/0x1c80\n\n## Affected\n\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 1371ef6b1ecf3676b8942f5dfb3634fb0648128e`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 362e45fd9069ffa1523f9f1633b606ebf72060d7`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 6eb2919474ca105c5b13d19574e25f0ddcf19ca2`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 9c80d688f402539dfc8f336de1380d6b4ee14316`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 205955f29c26330b1dc7fdeadd5bb97c38e26f56`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 52ab82cc5cf8ada5c3fb6ffe8f32fdb2fc27a34b`\n- `Linux >= 2be8e3ee8efd6f99ce454115c29d09750915021a < 5551b02fdbfd85a325bb857f3a8f9c9f33397ed2`\n- `Linux 2.6.24`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}