{"id":"CVE-2026-68278","summary":"drm/dp/mst: fix buffer overflows in sideband chunk accumulation","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/dp/mst: fix buffer overflows in sideband chunk accumulation\n\ndrm_dp_sideband_append_payload() has three related bugs when processing\ndevice-provided sideband reply data:\n\n1. Zero-length curchunk_len underflow: msg_len is a 6-bit field taken\n   directly from the DP sideband header. If a device sends msg_len=0,\n   curchunk_len is set to zero. The condition (curchunk_idx \u003e= curchunk_len)\n   is immediately true, and curchunk_len-1 wraps to 255 (u8 underflow).\n   drm_dp_msg_data_crc4() reads 255 bytes from chunk[48], then memcpy()\n   writes 255 bytes into msg[], both far out of bounds.\n\n2. chunk[48] overflow: curchunk_len can reach 63 (6-bit field). chunk[] is\n   only 48 bytes. Multi-iteration payload assembly appends 16-byte blocks\n   until curchunk_idx reaches curchunk_len, writing up to 15 bytes past\n   the end of chunk[] into msg[].\n\n3. msg[256] overflow: each chunk contributes (curchunk_len-1) bytes to\n   msg[]. No check ensures curlen + (curchunk_len-1) stays within msg[256],\n   so the memcpy can spill into adjacent struct fields.\n\nAll three are reachable from any DP MST device that can forge sideband\nreply messages on a physical connection.","modified":"2026-08-12T04:18:47.491968102Z","published":"2026-08-10T12:01:54.285Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68278.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1e5827839ad0ceb0079d1560c321fa3656b54f21"},{"type":"WEB","url":"https://git.kernel.org/stable/c/53937a2787d29c7a460e984dc4f20ff6ac91dc65"},{"type":"WEB","url":"https://git.kernel.org/stable/c/55bd5e685bda455b9b50c835f8c8442d52a344a3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a6366b551079c79bf7bdbadd74c97358bcfe2d58"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ef0dbcc200c3389f1f781ab181932a97e54b51af"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68278.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68278"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ad7f8a1f9ced7f049f9b66d588723f243a7034cd"},{"fixed":"53937a2787d29c7a460e984dc4f20ff6ac91dc65"},{"fixed":"ef0dbcc200c3389f1f781ab181932a97e54b51af"},{"fixed":"1e5827839ad0ceb0079d1560c321fa3656b54f21"},{"fixed":"a6366b551079c79bf7bdbadd74c97358bcfe2d58"},{"fixed":"55bd5e685bda455b9b50c835f8c8442d52a344a3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68278.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.17.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68278.json"}}],"schema_version":"1.9.0"}