{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-53827", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-09T01:27:17.825Z", "datePublished": "2025-12-09T01:29:40.794Z", "dateUpdated": "2026-08-05T09:16:16.899Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T09:16:16.899Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix use-after-free in l2cap_disconnect_{req,rsp}\n\nSimilar to commit d0be8347c623 (\"Bluetooth: L2CAP: Fix use-after-free\ncaused by l2cap_chan_put\"), just use l2cap_chan_hold_unless_zero to\nprevent referencing a channel that is about to be destroyed." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:A - The vulnerable code is reached only by processing an L2CAP Disconnect Request/Response signalling PDU received from a Bluetooth peer over a BR/EDR ACL or LE link, which requires the attacker to be within Bluetooth radio range. Per kernel scoring guidance, Bluetooth-reachable code is Adjacent.\nAC:L - The attacker drives both sides: it creates and tears down L2CAP channels at will (CONN_REQ/DISCONN_REQ, ECRED reconfigure responses that call l2cap_chan_del with no lock) while flooding disconnect signalling to hit the window where the kref has reached zero but the channel is still on conn->chan_l, and can retry the connect/disconnect cycle indefinitely at no cost. syzbot reproduced the identical pattern in the sibling handler.\nPR:N - l2cap_recv_frame dispatches CID 0x0001/0x0005 straight to the signalling handlers with no security-level, pairing, or encryption check, so an entirely unauthenticated, unpaired in-range device can send the triggering PDU. Fixed channels present on conn->chan_l give a valid target CID without any local socket.\nUI:N - No victim action is needed — the packet is processed by hci_rx_work as soon as it arrives on a connectable/advertising host with Bluetooth enabled, which is the default on phones, cars, headsets and laptops.\nS:U - The corruption and its consequences are confined to the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The handler reads chan->scid and chan->dcid out of the freed kmalloc-1k object and echoes them to the attacker in the Disconnect Response, giving a repeatable remote leak of reclaimed kernel heap contents, and the broader use-after-free permits arbitrary read via heap grooming.\nI:H - After the increment-on-zero the code performs three indirect calls (chan->ops->set_shutdown, ->teardown, ->close) through function pointers read from the freed object plus a list_del on freed list heads, so an attacker who sprays the reclaimed kmalloc-1024 slot obtains control-flow hijack and arbitrary-write primitives.\nA:H - The bug is a KASAN-confirmed use-after-free that mutex_locks freed memory and triggers a refcount_t \"increment on 0\" splat, reliably producing a kernel oops/panic, and it can be re-triggered remotely at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/l2cap_core.c" ], "versions": [ { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "f2d38e77aa5f3effc143e7dd24da8acf02925958", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "1351551aa9058e07a20a27a158270cf84fcde621", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "c02421992505c95c7f3c9ad59ee35e22eac60988", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "d9ba36c22a7bb09d6bac4cc2f243eff05da53f43", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "ac6725a634f7e8c0330610a8527f20c730b61115", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "348d446762e7c70778df8bafbdf3fa0df2123f58", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "d82a439c3cfdb28aa7e82e2e849c5c4dd9fca284", "status": "affected", "versionType": "git" }, { "version": "61d6ef3e3408cdf7e622646fb90a9f7f9560b943", "lessThan": "a2a9339e1c9deb7e1e079e12e27a0265aea8421a", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bluetooth/l2cap_core.c" ], "versions": [ { "version": "3.5", "status": "affected" }, { "version": "0", "lessThan": "3.5", "status": "unaffected", "versionType": "semver" }, { "version": "4.14.313", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.281", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.241", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.178", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.108", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.25", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.2.12", "lessThanOrEqual": "6.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.3", "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": "3.5", "versionEndExcluding": "4.14.313" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "4.19.281" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "5.4.241" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "5.10.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "5.15.108" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.1.25" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.2.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f2d38e77aa5f3effc143e7dd24da8acf02925958" }, { "url": "https://git.kernel.org/stable/c/1351551aa9058e07a20a27a158270cf84fcde621" }, { "url": "https://git.kernel.org/stable/c/c02421992505c95c7f3c9ad59ee35e22eac60988" }, { "url": "https://git.kernel.org/stable/c/d9ba36c22a7bb09d6bac4cc2f243eff05da53f43" }, { "url": "https://git.kernel.org/stable/c/ac6725a634f7e8c0330610a8527f20c730b61115" }, { "url": "https://git.kernel.org/stable/c/348d446762e7c70778df8bafbdf3fa0df2123f58" }, { "url": "https://git.kernel.org/stable/c/d82a439c3cfdb28aa7e82e2e849c5c4dd9fca284" }, { "url": "https://git.kernel.org/stable/c/a2a9339e1c9deb7e1e079e12e27a0265aea8421a" } ], "title": "Bluetooth: L2CAP: Fix use-after-free in l2cap_disconnect_{req,rsp}", "x_generator": { "engine": "bippy-1.2.0" } } } }