{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39863", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.143Z", "datePublished": "2025-09-19T15:26:33.069Z", "dateUpdated": "2026-08-05T12:05:43.455Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:05:43.455Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work\n\nThe brcmf_btcoex_detach() only shuts down the btcoex timer, if the\nflag timer_on is false. However, the brcmf_btcoex_timerfunc(), which\nruns as timer handler, sets timer_on to false. This creates critical\nrace conditions:\n\n1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc()\nis executing, it may observe timer_on as false and skip the call to\ntimer_shutdown_sync().\n\n2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info\nworker after the cancel_work_sync() has been executed, resulting in\nuse-after-free bugs.\n\nThe use-after-free bugs occur in two distinct scenarios, depending on\nthe timing of when the brcmf_btcoex_info struct is freed relative to\nthe execution of its worker thread.\n\nScenario 1: Freed before the worker is scheduled\n\nThe brcmf_btcoex_info is deallocated before the worker is scheduled.\nA race condition can occur when schedule_work(&bt_local->work) is\ncalled after the target memory has been freed. The sequence of events\nis detailed below:\n\nCPU0 | CPU1\nbrcmf_btcoex_detach | brcmf_btcoex_timerfunc\n | bt_local->timer_on = false;\n if (cfg->btcoex->timer_on) |\n ... |\n cancel_work_sync(); |\n ... |\n kfree(cfg->btcoex); // FREE |\n | schedule_work(&bt_local->work); // USE\n\nScenario 2: Freed after the worker is scheduled\n\nThe brcmf_btcoex_info is freed after the worker has been scheduled\nbut before or during its execution. In this case, statements within\nthe brcmf_btcoex_handler() — such as the container_of macro and\nsubsequent dereferences of the brcmf_btcoex_info object will cause\na use-after-free access. The following timeline illustrates this\nscenario:\n\nCPU0 | CPU1\nbrcmf_btcoex_detach | brcmf_btcoex_timerfunc\n | bt_local->timer_on = false;\n if (cfg->btcoex->timer_on) |\n ... |\n cancel_work_sync(); |\n ... | schedule_work(); // Reschedule\n |\n kfree(cfg->btcoex); // FREE | brcmf_btcoex_handler() // Worker\n /* | btci = container_of(....); // USE\n The kfree() above could | ...\n also occur at any point | btci-> // USE\n during the worker's execution|\n */ |\n\nTo resolve the race conditions, drop the conditional check and call\ntimer_shutdown_sync() directly. It can deactivate the timer reliably,\nregardless of its current state. Once stopped, the timer_on state is\nthen set to false." } ], "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 race is armed through a local nl80211/netlink command (NL80211_CMD_CRIT_PROTOCOL_START) on the local wireless device and freed through a local driver teardown/bus-reset path; no remote or adjacent-network frame reaches `brcmf_btcoex_detach()` or arms the btcoex timer directly. Although an adjacent attacker can induce the free side by halting the firmware (`BRCMF_D2H_DEV_FWHALT` → `brcmf_fw_crashed()` → `brcmf_bus_reset()`), a single attacker capable of both halves of the race operates locally.\nAC:L - The attacker controls both sides: the crit-proto `duration` makes the handler arm the timer at a deterministic `jiffies + 2s`, so the callback's execution moment is known in advance, and the same actor drives the teardown (bus reset / driver unbind / firmware halt) to land inside it. The attempt is cheap to repeat in a loop until the window is hit, and the freed `kmalloc-192` object can be sprayed with standard heap-grooming syscalls.\nPR:L - `NL80211_CMD_CRIT_PROTOCOL_START` carries `GENL_UNS_ADMIN_PERM` (CAP_NET_ADMIN), which on Android and embedded targets is held by the confined non-root Wi-Fi/supplicant service account rather than by real root in the init namespace, and the free side can be reached without root by making the firmware halt. Basic account-level access with that delegated network capability is sufficient, so this is Low rather than High.\nUI:N - The attacker issues the crit-proto start and triggers the teardown itself; no victim needs to mount a filesystem, open a file, or take any other action for the use-after-free to occur.\nS:U - The freed object, the corrupted slab, and the hijacked workqueue dispatch all live within the kernel's own security authority, with no crossing into a hypervisor, IOMMU, or other protection domain.\nC:H - The use-after-free lets the attacker reoccupy the freed `brcmf_btcoex_info` slot, after which `brcmf_btcoex_handler()` dereferences attacker-chosen `btci->vif`, `btci->vif->ifp`, and `btci->cfg->pub` pointers, yielding an arbitrary kernel-memory read primitive and disclosure of kernel addresses.\nI:H - `process_one_work()` loads `work->func` out of the freed structure and calls it (`worker->current_func = work->func; worker->current_func(work);`), so a resprayed slot gives a controlled indirect call, and `schedule_work()` on freed memory additionally corrupts worker-pool list linkage — a full control-flow-hijack and arbitrary-write primitive.\nA:H - Even without successful grooming, scheduling and executing work on a kfree'd object dereferences poisoned/recycled memory and reliably produces a KASAN splat, oops, or kernel panic, taking the system down." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c" ], "versions": [ { "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba", "lessThan": "c75600e69e66a751cc046cd9c407b942f298d852", "status": "affected", "versionType": "git" }, { "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba", "lessThan": "ae58f70bde0433f27ef4b388ab50634736607bf6", "status": "affected", "versionType": "git" }, { "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba", "lessThan": "f1150153c4e5940fe49ab51136343c5b4fe49d63", "status": "affected", "versionType": "git" }, { "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba", "lessThan": "3e789f8475f6c857c88de5c5bf4b24b11a477dd7", "status": "affected", "versionType": "git" }, { "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba", "lessThan": "2f6fbc8e04ca1d1d5c560be694199f847229c625", "status": "affected", "versionType": "git" }, { "version": "61730d4dfffc2cc9d3a49fad87633008105c18ba", "lessThan": "9cb83d4be0b9b697eae93d321e0da999f9cdfcfc", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/wireless/broadcom/brcm80211/brcmfmac/btcoex.c" ], "versions": [ { "version": "3.10", "status": "affected" }, { "version": "0", "lessThan": "3.10", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.105", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.46", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.6", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "3.10", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.1.167" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.6.105" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.12.46" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.16.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c75600e69e66a751cc046cd9c407b942f298d852" }, { "url": "https://git.kernel.org/stable/c/ae58f70bde0433f27ef4b388ab50634736607bf6" }, { "url": "https://git.kernel.org/stable/c/f1150153c4e5940fe49ab51136343c5b4fe49d63" }, { "url": "https://git.kernel.org/stable/c/3e789f8475f6c857c88de5c5bf4b24b11a477dd7" }, { "url": "https://git.kernel.org/stable/c/2f6fbc8e04ca1d1d5c560be694199f847229c625" }, { "url": "https://git.kernel.org/stable/c/9cb83d4be0b9b697eae93d321e0da999f9cdfcfc" } ], "title": "wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2025-39863", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-01-14T19:23:53.735650Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-01-14T19:33:11.612Z" } } ] } }