{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31772", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.140Z", "datePublished": "2026-05-01T14:15:00.582Z", "dateUpdated": "2026-08-05T12:25:04.625Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:25:04.625Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync\n\nhci_le_big_create_sync() uses DEFINE_FLEX to allocate a\nstruct hci_cp_le_big_create_sync on the stack with room for 0x11 (17)\nBIS entries. However, conn->num_bis can hold up to HCI_MAX_ISO_BIS (31)\nentries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller\nhci_conn_big_create_sync(). When conn->num_bis is between 18 and 31,\nthe memcpy that copies conn->bis into cp->bis writes up to 14 bytes\npast the stack buffer, corrupting adjacent stack memory.\n\nThis is trivially reproducible: binding an ISO socket with\nbc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will\neventually trigger hci_le_big_create_sync() from the HCI command\nsync worker, causing a KASAN-detectable stack-out-of-bounds write:\n\n BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0\n Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71\n\nFix this by changing the DEFINE_FLEX count from the incorrect 0x11 to\nHCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that\nconn->bis can actually carry." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The overflow is reached through locally created AF_BLUETOOTH ISO sockets via bind/listen or deferred receive; the Bluetooth BIG Info event only completes a userspace-initiated ISO sync path.\nAC:L - An attacker can choose a valid bc_num_bis value from 18 to 31 and valid BIS indexes, with no race or hard-to-control memory condition required.\nPR:L - Creating, binding, and listening on BTPROTO_ISO sockets does not require CAP_NET_ADMIN or other elevated capabilities, but it does require local code execution as an unprivileged user.\nUI:N - The attacker can trigger the vulnerable socket operations and resulting HCI sync worker path without any victim action.\nS:U - The corruption occurs within the kernel and affects the same operating-system security authority; ordinary kernel privilege escalation remains scope unchanged.\nC:H - This is kernel stack memory corruption from an out-of-bounds write, which can plausibly be leveraged to disclose sensitive kernel memory when exploited.\nI:H - The bug is a controlled out-of-bounds write past a stack buffer in kernel context, making high-integrity impact defensible.\nA:H - The issue is KASAN-reproducible as a stack out-of-bounds write in a kernel worker and can crash or destabilize the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/hci_sync.c" ], "versions": [ { "version": "91d19383b7ed035e22165ae5c836e50bb9f95fbe", "lessThan": "f5d446624345d309e7a4a1b27ea9f028d6a8c5d9", "status": "affected", "versionType": "git" }, { "version": "42ecf1947135110ea08abeaca39741636f9a2285", "lessThan": "aba0aea354015794e8312dd7efe726967e58aefe", "status": "affected", "versionType": "git" }, { "version": "42ecf1947135110ea08abeaca39741636f9a2285", "lessThan": "eaf32002ca7b1ba51c9f140991fd9febe6de79f0", "status": "affected", "versionType": "git" }, { "version": "42ecf1947135110ea08abeaca39741636f9a2285", "lessThan": "bc39a094730ce062fa034a529c93147c096cb488", "status": "affected", "versionType": "git" }, { "version": "8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd", "status": "affected", "versionType": "git" }, { "version": "6.12.2", "lessThan": "6.12.81", "status": "affected", "versionType": "semver" }, { "version": "6.11.11", "lessThan": "6.12", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/hci_sync.c" ], "versions": [ { "version": "6.13", "status": "affected" }, { "version": "0", "lessThan": "6.13", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.81", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.22", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.12", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.2", "versionEndExcluding": "6.12.81" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.19.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.0" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.11.11" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f5d446624345d309e7a4a1b27ea9f028d6a8c5d9" }, { "url": "https://git.kernel.org/stable/c/aba0aea354015794e8312dd7efe726967e58aefe" }, { "url": "https://git.kernel.org/stable/c/eaf32002ca7b1ba51c9f140991fd9febe6de79f0" }, { "url": "https://git.kernel.org/stable/c/bc39a094730ce062fa034a529c93147c096cb488" } ], "title": "Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync", "x_generator": { "engine": "bippy-1.2.0" } } } }