{"api_version":"1","generated_at":"2026-08-22T19:29:53+00:00","cve":"CVE-2026-68124","urls":{"html":"https://cve.report/CVE-2026-68124","api":"https://cve.report/api/cve/CVE-2026-68124.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-68124","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-68124"},"summary":{"title":"mctp: serial: handle zero-length frames to prevent rx buffer overflow","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: serial: handle zero-length frames to prevent rx buffer overflow\n\nThe MCTP serial receive state machine reads a frame length byte in\nmctp_serial_push_header() case 2 and validates it upper-bound-only:\n\n\tif (c > MCTP_SERIAL_FRAME_MTU) {\n\t\tdev->rxstate = STATE_ERR;\n\t} else {\n\t\tdev->rxlen = c;\n\t\tdev->rxpos = 0;\n\t\tdev->rxstate = STATE_DATA;\n\t\t...\n\t}\n\nA length of zero passes this check, so rxlen is set to 0 and the state\nmachine advances to STATE_DATA. In mctp_serial_push() STATE_DATA, the\nincoming byte is stored and rxpos incremented before the terminator is\n\n\tdev->rxbuf[dev->rxpos] = c;\n\tdev->rxpos++;\n\tdev->rxstate = STATE_DATA;\n\tif (dev->rxpos == dev->rxlen) {\n\t\tdev->rxpos = 0;\n\t\tdev->rxstate = STATE_TRAILER;\n\t}\n\nWith rxlen == 0 the \"rxpos == rxlen\" terminator can never fire (rxpos is\nalready 1 on the first data byte), so subsequent bytes are written past\nthe end of the fixed 74-byte rxbuf, which is the last member of the\nnetdev private area. Every following data byte is an attacker-controlled\n1-byte out-of-bounds heap write, and the overflow continues until a\nframe (0x7e) or escape byte resets the parser -- effectively unbounded.\n\nReaching this requires CAP_NET_ADMIN to attach the N_MCTP line\ndiscipline and bring the resulting mctpserialN netdev up, after which\nthe bytes arrive via the tty receive path.\n\nRoute a zero-length frame straight to STATE_TRAILER instead of\nSTATE_DATA. The trailer/framing bytes are still consumed, and the frame\nresolves to a zero-length skb that the MCTP core rejects; the parser\nnever enters STATE_DATA with rxlen == 0, so the out-of-bounds write can\nno longer occur.\n\nKASAN, on a frame of 0x7e 0x01 0x00 followed by data bytes (before this\nchange):\n\n  UBSAN: array-index-out-of-bounds in drivers/net/mctp/mctp-serial.c:370\n  index 74 is out of range for type 'u8 [74]'\n  BUG: KASAN: slab-out-of-bounds in mctp_serial_tty_receive_buf\n  Write of size 1 at addr ... by task kworker/u16:0\n   mctp_serial_tty_receive_buf\n   tty_ldisc_receive_buf\n   flush_to_ldisc\n  Allocated by task 152:\n   alloc_netdev_mqs\n   mctp_serial_open\n\nv2: route zero-length frames to STATE_TRAILER instead of STATE_ERR so\n    the trailer/framing bytes are still consumed (Jeremy Kerr).\n\nFound by 0sec automated security-research tooling (https://0sec.ai).","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-10 13:19:57","updated_at":"2026-08-19 17:20:29"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.6","severity":"CRITICAL","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","baseScore":9.6,"baseSeverity":"CRITICAL","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.6","severity":"CRITICAL","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","data":{"baseScore":9.6,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/64b96ae7912244d55257aa330d9569ee0a8f8d99","name":"https://git.kernel.org/stable/c/64b96ae7912244d55257aa330d9569ee0a8f8d99","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/793b9b729f1e8de57be8c8daf1a9838be96cabed","name":"https://git.kernel.org/stable/c/793b9b729f1e8de57be8c8daf1a9838be96cabed","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/36dc6d6964a3b90411cc7944cd9b8b6f67b9807b","name":"https://git.kernel.org/stable/c/36dc6d6964a3b90411cc7944cd9b8b6f67b9807b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/06a6b606129c8a25cd457760f5370f3ff01fe05d","name":"https://git.kernel.org/stable/c/06a6b606129c8a25cd457760f5370f3ff01fe05d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f80ba170d7b3a44e3d244a2c8e06031d61bf3b23","name":"https://git.kernel.org/stable/c/f80ba170d7b3a44e3d244a2c8e06031d61bf3b23","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/68819427bc07eca7963a9e8be19e5272cc29186c","name":"https://git.kernel.org/stable/c/68819427bc07eca7963a9e8be19e5272cc29186c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-68124","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68124","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd 64b96ae7912244d55257aa330d9569ee0a8f8d99 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd 36dc6d6964a3b90411cc7944cd9b8b6f67b9807b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd 68819427bc07eca7963a9e8be19e5272cc29186c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd f80ba170d7b3a44e3d244a2c8e06031d61bf3b23 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd 06a6b606129c8a25cd457760f5370f3ff01fe05d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd 793b9b729f1e8de57be8c8daf1a9838be96cabed git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.17","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.17 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.183 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.148 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.101 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.42 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.6 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"68124","cve":"CVE-2026-68124","epss":"0.003440000","percentile":"0.275320000","score_date":"2026-08-19","updated_at":"2026-08-20 00:13:09"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/net/mctp/mctp-serial.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"64b96ae7912244d55257aa330d9569ee0a8f8d99","status":"affected","version":"a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd","versionType":"git"},{"lessThan":"36dc6d6964a3b90411cc7944cd9b8b6f67b9807b","status":"affected","version":"a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd","versionType":"git"},{"lessThan":"68819427bc07eca7963a9e8be19e5272cc29186c","status":"affected","version":"a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd","versionType":"git"},{"lessThan":"f80ba170d7b3a44e3d244a2c8e06031d61bf3b23","status":"affected","version":"a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd","versionType":"git"},{"lessThan":"06a6b606129c8a25cd457760f5370f3ff01fe05d","status":"affected","version":"a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd","versionType":"git"},{"lessThan":"793b9b729f1e8de57be8c8daf1a9838be96cabed","status":"affected","version":"a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/net/mctp/mctp-serial.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.17"},{"lessThan":"5.17","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.183","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.148","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.101","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.42","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.183","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.148","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.101","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.42","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.6","versionStartIncluding":"5.17","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"5.17","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: serial: handle zero-length frames to prevent rx buffer overflow\n\nThe MCTP serial receive state machine reads a frame length byte in\nmctp_serial_push_header() case 2 and validates it upper-bound-only:\n\n\tif (c > MCTP_SERIAL_FRAME_MTU) {\n\t\tdev->rxstate = STATE_ERR;\n\t} else {\n\t\tdev->rxlen = c;\n\t\tdev->rxpos = 0;\n\t\tdev->rxstate = STATE_DATA;\n\t\t...\n\t}\n\nA length of zero passes this check, so rxlen is set to 0 and the state\nmachine advances to STATE_DATA. In mctp_serial_push() STATE_DATA, the\nincoming byte is stored and rxpos incremented before the terminator is\n\n\tdev->rxbuf[dev->rxpos] = c;\n\tdev->rxpos++;\n\tdev->rxstate = STATE_DATA;\n\tif (dev->rxpos == dev->rxlen) {\n\t\tdev->rxpos = 0;\n\t\tdev->rxstate = STATE_TRAILER;\n\t}\n\nWith rxlen == 0 the \"rxpos == rxlen\" terminator can never fire (rxpos is\nalready 1 on the first data byte), so subsequent bytes are written past\nthe end of the fixed 74-byte rxbuf, which is the last member of the\nnetdev private area. Every following data byte is an attacker-controlled\n1-byte out-of-bounds heap write, and the overflow continues until a\nframe (0x7e) or escape byte resets the parser -- effectively unbounded.\n\nReaching this requires CAP_NET_ADMIN to attach the N_MCTP line\ndiscipline and bring the resulting mctpserialN netdev up, after which\nthe bytes arrive via the tty receive path.\n\nRoute a zero-length frame straight to STATE_TRAILER instead of\nSTATE_DATA. The trailer/framing bytes are still consumed, and the frame\nresolves to a zero-length skb that the MCTP core rejects; the parser\nnever enters STATE_DATA with rxlen == 0, so the out-of-bounds write can\nno longer occur.\n\nKASAN, on a frame of 0x7e 0x01 0x00 followed by data bytes (before this\nchange):\n\n  UBSAN: array-index-out-of-bounds in drivers/net/mctp/mctp-serial.c:370\n  index 74 is out of range for type 'u8 [74]'\n  BUG: KASAN: slab-out-of-bounds in mctp_serial_tty_receive_buf\n  Write of size 1 at addr ... by task kworker/u16:0\n   mctp_serial_tty_receive_buf\n   tty_ldisc_receive_buf\n   flush_to_ldisc\n  Allocated by task 152:\n   alloc_netdev_mqs\n   mctp_serial_open\n\nv2: route zero-length frames to STATE_TRAILER instead of STATE_ERR so\n    the trailer/framing bytes are still consumed (Jeremy Kerr).\n\nFound by 0sec automated security-research tooling (https://0sec.ai)."}],"metrics":[{"cvssV3_1":{"baseScore":9.6,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:A - The bug is triggered in mctp_serial_tty_receive_buf() by crafted DSP0253 serial frames; on BMC/datacenter systems MCTP-over-serial links management controllers on a shared management LAN, letting an adjacent unauthenticated peer inject 0x7e/0x01/0x00 frames without using host syscalls.\nAC:L - Exploitation is deterministic: a zero-length length byte bypasses the upper-bound check, then each following serial byte is a controlled 1-byte heap OOB write until 0x7e/0x7d resets the parser; no races or attacker-uncontrollable memory layout are required.\nPR:N - Triggering the overflow only requires delivering malicious serial bytes to an already-configured, running mctpserial netdev; a remote/adjacent MCTP peer or compromised management controller needs no Linux host credentials, CAP_NET_ADMIN, or root on the victim.\nUI:N - No victim user action is required at exploit time; administrative enablement of MCTP serial is deployment configuration, not end-user interaction under CVSS.\nS:C - Kconfig documents virtio-serial VM interconnect for MCTP serial; a malicious guest sending crafted frames to the host-side mctpserial binding can corrupt host kernel heap memory, crossing the guest/host virtualization security boundary.\nC:H - Each overflow byte is attacker-controlled and the write stream is effectively unbounded past the 74-byte rxbuf (last netdev private field), enabling slab-out-of-bounds corruption that can be leveraged for arbitrary kernel memory disclosure.\nI:H - Sustained attacker-controlled out-of-bounds heap writes can corrupt adjacent kmalloc objects, function pointers, and netdev state, providing a standard path to arbitrary kernel write and privilege-escalating code execution.\nA:H - KASAN/UBSAN report slab-out-of-bounds and array-index-out-of-bounds in mctp_serial_tty_receive_buf via flush_to_ldisc; continued overflow reliably causes kernel oops/panic or hang during tty receive processing."}]}],"providerMetadata":{"dateUpdated":"2026-08-19T16:29:36.851Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/64b96ae7912244d55257aa330d9569ee0a8f8d99"},{"url":"https://git.kernel.org/stable/c/36dc6d6964a3b90411cc7944cd9b8b6f67b9807b"},{"url":"https://git.kernel.org/stable/c/68819427bc07eca7963a9e8be19e5272cc29186c"},{"url":"https://git.kernel.org/stable/c/f80ba170d7b3a44e3d244a2c8e06031d61bf3b23"},{"url":"https://git.kernel.org/stable/c/06a6b606129c8a25cd457760f5370f3ff01fe05d"},{"url":"https://git.kernel.org/stable/c/793b9b729f1e8de57be8c8daf1a9838be96cabed"}],"title":"mctp: serial: handle zero-length frames to prevent rx buffer overflow","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-68124","datePublished":"2026-08-10T11:58:44.997Z","dateReserved":"2026-07-30T09:28:09.369Z","dateUpdated":"2026-08-19T16:29:36.851Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-10 13:19:57","lastModifiedDate":"2026-08-19 17:20:29","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","baseScore":9.6,"baseSeverity":"CRITICAL","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2.8,"impactScore":6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"68124","Ordinal":"1","Title":"mctp: serial: handle zero-length frames to prevent rx buffer ove","CVE":"CVE-2026-68124","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"68124","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmctp: serial: handle zero-length frames to prevent rx buffer overflow\n\nThe MCTP serial receive state machine reads a frame length byte in\nmctp_serial_push_header() case 2 and validates it upper-bound-only:\n\n\tif (c > MCTP_SERIAL_FRAME_MTU) {\n\t\tdev->rxstate = STATE_ERR;\n\t} else {\n\t\tdev->rxlen = c;\n\t\tdev->rxpos = 0;\n\t\tdev->rxstate = STATE_DATA;\n\t\t...\n\t}\n\nA length of zero passes this check, so rxlen is set to 0 and the state\nmachine advances to STATE_DATA. In mctp_serial_push() STATE_DATA, the\nincoming byte is stored and rxpos incremented before the terminator is\n\n\tdev->rxbuf[dev->rxpos] = c;\n\tdev->rxpos++;\n\tdev->rxstate = STATE_DATA;\n\tif (dev->rxpos == dev->rxlen) {\n\t\tdev->rxpos = 0;\n\t\tdev->rxstate = STATE_TRAILER;\n\t}\n\nWith rxlen == 0 the \"rxpos == rxlen\" terminator can never fire (rxpos is\nalready 1 on the first data byte), so subsequent bytes are written past\nthe end of the fixed 74-byte rxbuf, which is the last member of the\nnetdev private area. Every following data byte is an attacker-controlled\n1-byte out-of-bounds heap write, and the overflow continues until a\nframe (0x7e) or escape byte resets the parser -- effectively unbounded.\n\nReaching this requires CAP_NET_ADMIN to attach the N_MCTP line\ndiscipline and bring the resulting mctpserialN netdev up, after which\nthe bytes arrive via the tty receive path.\n\nRoute a zero-length frame straight to STATE_TRAILER instead of\nSTATE_DATA. The trailer/framing bytes are still consumed, and the frame\nresolves to a zero-length skb that the MCTP core rejects; the parser\nnever enters STATE_DATA with rxlen == 0, so the out-of-bounds write can\nno longer occur.\n\nKASAN, on a frame of 0x7e 0x01 0x00 followed by data bytes (before this\nchange):\n\n  UBSAN: array-index-out-of-bounds in drivers/net/mctp/mctp-serial.c:370\n  index 74 is out of range for type 'u8 [74]'\n  BUG: KASAN: slab-out-of-bounds in mctp_serial_tty_receive_buf\n  Write of size 1 at addr ... by task kworker/u16:0\n   mctp_serial_tty_receive_buf\n   tty_ldisc_receive_buf\n   flush_to_ldisc\n  Allocated by task 152:\n   alloc_netdev_mqs\n   mctp_serial_open\n\nv2: route zero-length frames to STATE_TRAILER instead of STATE_ERR so\n    the trailer/framing bytes are still consumed (Jeremy Kerr).\n\nFound by 0sec automated security-research tooling (https://0sec.ai).","Type":"Description","Title":"mctp: serial: handle zero-length frames to prevent rx buffer ove"}]}}}