{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-68124", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-68124", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-08-10T11:58:44.997Z", "updatedAt": "2026-08-19T16:29:36.851Z", "importedAt": "2026-10-24T01:58:25.636Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "mctp: serial: handle zero-length frames to prevent rx buffer overflow", "summary": "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).", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd", "status": "affected", "versionType": "git", "lessThan": "64b96ae7912244d55257aa330d9569ee0a8f8d99" }, { "version": "a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd", "status": "affected", "versionType": "git", "lessThan": "36dc6d6964a3b90411cc7944cd9b8b6f67b9807b" }, { "version": "a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd", "status": "affected", "versionType": "git", "lessThan": "68819427bc07eca7963a9e8be19e5272cc29186c" }, { "version": "a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd", "status": "affected", "versionType": "git", "lessThan": "f80ba170d7b3a44e3d244a2c8e06031d61bf3b23" }, { "version": "a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd", "status": "affected", "versionType": "git", "lessThan": "06a6b606129c8a25cd457760f5370f3ff01fe05d" }, { "version": "a0c2ccd9b5ad0a9e838158404e041b5a8ff762dd", "status": "affected", "versionType": "git", "lessThan": "793b9b729f1e8de57be8c8daf1a9838be96cabed" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "5.17", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "5.17" }, { "version": "6.1.183", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.148", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.101", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.42", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.1.6", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }