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GHSA-XF88-XMXW-HHCH

Vulnerability from github – Published: 2026-08-15 15:30 – Updated: 2026-08-17 06:33

Details

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero

hci_conn::iso_data is accessed and modified without lock or RCU. This leads to a race

[Task hdev->workqueue]                  [Task 2]
iso_recv                                    iso_conn_put(conn)
  conn = LOAD hcon->iso_data                  iso_conn_free(conn)
  iso_conn_hold_unless_zero(conn)               hcon->iso_data = NULL
                                                kfree(conn)
    kref_get_unless_zero(&conn->ref) /* UAF */

and also to races in iso_conn_add() vs. iso_conn_free().

Fix by adding spinlock hci_conn::proto_lock and using it to guard hci_conn::iso_data.

Severity

8.8 (High)


                  
                    CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74533"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T13:17:58Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: ISO: fix race of kfree vs kref_get_unless_zero\n\nhci_conn::iso_data is accessed and modified without lock or RCU.\nThis leads to a race\n\n    [Task hdev-\u003eworkqueue]                 \t[Task 2]\n    iso_recv                                    iso_conn_put(conn)\n      conn = LOAD hcon-\u003eiso_data                  iso_conn_free(conn)\n      iso_conn_hold_unless_zero(conn)               hcon-\u003eiso_data = NULL\n                                                    kfree(conn)\n        kref_get_unless_zero(\u0026conn-\u003eref) /* UAF */\n\nand also to races in iso_conn_add() vs. iso_conn_free().\n\nFix by adding spinlock hci_conn::proto_lock and using it to guard\nhci_conn::iso_data.",
  "id": "GHSA-xf88-xmxw-hhch",
  "modified": "2026-08-17T06:33:50Z",
  "published": "2026-08-15T15:30:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74533"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/876a3e94c70d0859d1dad1c986112d4f0d99eba8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-74533 (GCVE-0-2026-74533)

Vulnerability from cvelistv5 – Published: 2026-08-15 12:27 – Updated: 2026-08-17 05:48

Title

Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero

Summary

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero hci_conn::iso_data is accessed and modified without lock or RCU. This leads to a race [Task hdev->workqueue] [Task 2] iso_recv iso_conn_put(conn) conn = LOAD hcon->iso_data iso_conn_free(conn) iso_conn_hold_unless_zero(conn) hcon->iso_data = NULL kfree(conn) kref_get_unless_zero(&conn->ref) /* UAF */ and also to races in iso_conn_add() vs. iso_conn_free(). Fix by adding spinlock hci_conn::proto_lock and using it to guard hci_conn::iso_data.

Severity

8.8 (High)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root Scorecard

References

2 references

URL	Tags
https://git.kernel.org/stable/c/876a3e94c70d0859d…
https://git.kernel.org/stable/c/af24e338bf5dafb80…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: dc26097bdb864a0d5955b9a25e43376ffc1af99b , < 876a3e94c70d0859d1dad1c986112d4f0d99eba8 (git) Affected: dc26097bdb864a0d5955b9a25e43376ffc1af99b , < af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c (git) Affected: f53e7489273dc2bb307bf50f319b3762d45534f0 (git) Affected: a58d0f5dac322e16cc75334d000666512341bde5 (git) Affected: 6.11.11 , < 6.12 (semver) Affected: 6.12.2 , < 6.13 (semver)
Linux	Linux	Affected: 6.13 Unaffected: 0 , < 6.13 (semver) Unaffected: 7.1.8 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/bluetooth/hci_core.h",
            "net/bluetooth/hci_conn.c",
            "net/bluetooth/iso.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "876a3e94c70d0859d1dad1c986112d4f0d99eba8",
              "status": "affected",
              "version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
              "versionType": "git"
            },
            {
              "lessThan": "af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c",
              "status": "affected",
              "version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f53e7489273dc2bb307bf50f319b3762d45534f0",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a58d0f5dac322e16cc75334d000666512341bde5",
              "versionType": "git"
            },
            {
              "lessThan": "6.12",
              "status": "affected",
              "version": "6.11.11",
              "versionType": "semver"
            },
            {
              "lessThan": "6.13",
              "status": "affected",
              "version": "6.12.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/bluetooth/hci_core.h",
            "net/bluetooth/hci_conn.c",
            "net/bluetooth/iso.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": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "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": "7.1.8",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.11.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.12.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: ISO: fix race of kfree vs kref_get_unless_zero\n\nhci_conn::iso_data is accessed and modified without lock or RCU.\nThis leads to a race\n\n    [Task hdev-\u003eworkqueue]                 \t[Task 2]\n    iso_recv                                    iso_conn_put(conn)\n      conn = LOAD hcon-\u003eiso_data                  iso_conn_free(conn)\n      iso_conn_hold_unless_zero(conn)               hcon-\u003eiso_data = NULL\n                                                    kfree(conn)\n        kref_get_unless_zero(\u0026conn-\u003eref) /* UAF */\n\nand also to races in iso_conn_add() vs. iso_conn_free().\n\nFix by adding spinlock hci_conn::proto_lock and using it to guard\nhci_conn::iso_data."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The bug is in Bluetooth ISO receive handling (iso_recv in net/bluetooth/iso.c), reached when HCI processes ISO data packets from an adjacent BLE CIS/BIS/LE Audio peer via hci_recv_frame and hdev-\u003eworkqueue; per kernel guidance Bluetooth radio reachability is Adjacent.\nAC:L - The race is between iso_recv loading hcon-\u003eiso_data and iso_conn_free kfree-ing the same iso_conn; an attacker controls both sides by concurrently sending ISO HCI data while disconnecting or closing the ISO socket, without relying on uncontrollable memory layout.\nPR:N - BTPROTO_ISO sockets require no CAP_NET_ADMIN or CAP_NET_RAW; an unprivileged local process can open and tear down ISO connections, and an adjacent Bluetooth peer can drive iso_recv and hci disconnect events without any credentials on the victim host.\nUI:N - No victim interaction is needed during exploitation of an active ISO session; a remote peer can race incoming ISO packets against link teardown, and a local attacker can close its own ISO socket while receiving data without opening files or mounts.\nS:U - The UAF corrupts kernel heap memory in the Bluetooth ISO subsystem on the host, enabling standard local privilege escalation within the kernel boundary rather than crossing VM, container, or IOMMU isolation.\nC:H - iso_conn_hold_unless_zero calls kref_get_unless_zero on a freed iso_conn slab object after iso_conn_free kfree, and iso_recv then dereferences conn fields, a classic use-after-free enabling arbitrary kernel memory disclosure.\nI:H - The UAF on iso_conn (kref, spinlock, sk_buff and socket pointers) permits heap spraying and corruption of conn-\u003erx_skb/rx_len, providing primitives chainable to arbitrary kernel writes and control-flow hijacking.\nA:H - The use-after-free in iso_conn_hold_unless_zero during concurrent iso_recv and iso_conn_put reliably causes kernel oops or panic on freed slab memory, meeting High availability impact per kernel CVSS guidance for UAF crashes."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:48:22.228Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/876a3e94c70d0859d1dad1c986112d4f0d99eba8"
        },
        {
          "url": "https://git.kernel.org/stable/c/af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c"
        }
      ],
      "title": "Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74533",
    "datePublished": "2026-08-15T12:27:47.219Z",
    "dateReserved": "2026-08-15T05:44:03.912Z",
    "dateUpdated": "2026-08-17T05:48:22.228Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-XF88-XMXW-HHCH

CVE-2026-74533 (GCVE-0-2026-74533)

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