CVE-2026-31772 (GCVE-0-2026-31772)
Vulnerability from cvelistv5
Published
2026-05-01 14:15
Modified
2026-08-05 12:25
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync hci_le_big_create_sync() uses DEFINE_FLEX to allocate a struct hci_cp_le_big_create_sync on the stack with room for 0x11 (17) BIS entries. However, conn->num_bis can hold up to HCI_MAX_ISO_BIS (31) entries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller hci_conn_big_create_sync(). When conn->num_bis is between 18 and 31, the memcpy that copies conn->bis into cp->bis writes up to 14 bytes past the stack buffer, corrupting adjacent stack memory. This is trivially reproducible: binding an ISO socket with bc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will eventually trigger hci_le_big_create_sync() from the HCI command sync worker, causing a KASAN-detectable stack-out-of-bounds write: BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0 Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71 Fix this by changing the DEFINE_FLEX count from the incorrect 0x11 to HCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that conn->bis can actually carry.
References
Impacted products
Vendor Product Version
Linux Linux Version: 91d19383b7ed035e22165ae5c836e50bb9f95fbe
Version: 42ecf1947135110ea08abeaca39741636f9a2285
Version: 42ecf1947135110ea08abeaca39741636f9a2285
Version: 42ecf1947135110ea08abeaca39741636f9a2285
Version: 8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd
Version: 6.12.2   ≤
Version: 6.11.11   ≤
Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_sync.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f5d446624345d309e7a4a1b27ea9f028d6a8c5d9",
              "status": "affected",
              "version": "91d19383b7ed035e22165ae5c836e50bb9f95fbe",
              "versionType": "git"
            },
            {
              "lessThan": "aba0aea354015794e8312dd7efe726967e58aefe",
              "status": "affected",
              "version": "42ecf1947135110ea08abeaca39741636f9a2285",
              "versionType": "git"
            },
            {
              "lessThan": "eaf32002ca7b1ba51c9f140991fd9febe6de79f0",
              "status": "affected",
              "version": "42ecf1947135110ea08abeaca39741636f9a2285",
              "versionType": "git"
            },
            {
              "lessThan": "bc39a094730ce062fa034a529c93147c096cb488",
              "status": "affected",
              "version": "42ecf1947135110ea08abeaca39741636f9a2285",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8958e1cee4e2eac1a5b825caa4dd96ce9ed975dd",
              "versionType": "git"
            },
            {
              "lessThan": "6.12.81",
              "status": "affected",
              "version": "6.12.2",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12",
              "status": "affected",
              "version": "6.11.11",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_sync.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.81",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.22",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.81",
                  "versionStartIncluding": "6.12.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.22",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.12",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.11.11",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003enum_bis can hold up to HCI_MAX_ISO_BIS (31)\nentries \u2014 validated against ISO_MAX_NUM_BIS (0x1f) in the caller\nhci_conn_big_create_sync().  When conn-\u003enum_bis is between 18 and 31,\nthe memcpy that copies conn-\u003ebis into cp-\u003ebis 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-\u003ebis can actually carry."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:25:04.625Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31772",
    "datePublished": "2026-05-01T14:15:00.582Z",
    "dateReserved": "2026-03-09T15:48:24.140Z",
    "dateUpdated": "2026-08-05T12:25:04.625Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.