{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-80975", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.810Z", "datePublished": "2026-09-11T19:42:37.086Z", "dateUpdated": "2026-09-13T06:28:39.317Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-13T06:28:39.317Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmfd: qnap-mcu: keep the reply buffer alive past a command timeout\n\nqnap_mcu_exec() publishes an on-stack buffer to the receive path:\n\n\tunsigned char rx[QNAP_MCU_RX_BUFFER_SIZE];\n\t...\n\treply->data = rx;\n\treply->length = length;\n\nand qnap_mcu_receive_buf() writes into it from the serdev receive path,\nwhich runs out of flush_to_ldisc() and is not serialized against\nqnap_mcu_exec() at all. bus_lock cannot cover it, because qnap_mcu_exec()\nholds that mutex across wait_for_completion_timeout().\n\nOn a timeout qnap_mcu_exec() returns with reply->data still pointing at\nits own frame. A reply that arrives late, or an unsolicited message from\nthe MCU, is then written into a stack frame that has been left, corrupting\nwhatever runs next on that stack. The same applies when qnap_mcu_write()\nfails, since that path returns without touching the reply state either.\n\nMove the receive buffer into struct qnap_mcu. It is 37 bytes and the\nstructure is devm_kzalloc()ed, so it lives as long as the driver, and a\nlate write lands in memory that is still valid and is reinitialized by the\nnext command. bus_lock keeps commands from sharing it.\n\nThis deliberately does not clear reply->data or reply->length on the\ntimeout path. Doing so races with qnap_mcu_receive_buf(), which reads both\nafter its\n\n\tif (!reply->length)\n\t\treturn size;\n\ncheck: clearing reply->data gives a NULL dereference, and clearing\nreply->length alone removes the reply->received == reply->length exit\ncondition, so the copy loop runs until the uart chunk is consumed and\noverruns the buffer. Leaving both set keeps the write bounded by\nreply->length, which qnap_mcu_exec() has already checked against\nsizeof(mcu->rx)."}], "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 bug is reached only through local qnap_mcu_exec() calls from hwmon/nvmem/LED/input/thermal sysfs on QNAP NAS devices whose MCU is a soldered UART serdev child, not a network protocol or a user-pluggable USB device, so the vector is Local rather than Physical.\nAC:L - This is use-after-return of an on-stack RX buffer published to qnap_mcu_receive_buf(), which runs from flush_to_ldisc() with no lock shared with qnap_mcu_exec(); an attacker issues commands via sysfs, retries at will, and after the 500 ms timeout reply->data still points at their kernel stack so a late or unsolicited MCU chunk writes into that frame.\nPR:L - Fan/temp hwmon attributes are mode 0444 and pwm is 0644, and the EEPROM nvmem is registered with root_only=false (0444), so any unprivileged local user can invoke qnap_mcu_exec() by reading those sysfs files without capabilities or init-namespace root.\nUI:N - Exploitation uses the attacker\u2019s own reads of already-present hwmon and nvmem sysfs; no victim must mount a filesystem, plug in hardware, or otherwise act, and thermal cooling plus input polling can also enter the same path automatically.\nS:U - The use-after-return corrupts the kernel stack of the task or kworker that called qnap_mcu_exec() on the same host; it does not cross a VM, IOMMU, or sandbox boundary into a separate security authority.\nC:H - A late UART write of up to 37 bytes into a returned kernel stack frame is use-after-return memory corruption; the attacker can groom that stack with a follow-up syscall so the overwrite becomes a kernel read primitive, which per UAF guidance is High confidentiality impact.\nI:H - The same write into the abandoned stack can smash return addresses, saved registers, and pointers of the next function on that stack, including after attacker-controlled syscall grooming, yielding control-flow hijack; use-after-return stack corruption is High integrity impact.\nA:H - Writing MCU UART bytes into a kernel stack frame that has already been left corrupts in-use stack state and causes an oops or panic even when not turned into a full exploit, fully denying availability."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/mfd/qnap-mcu.c"], "versions": [{"version": "998f70d1806bb718a7565f350283e4a79c8cbb4b", "lessThan": "0b6680e306397097a97767447368221fac753809", "status": "affected", "versionType": "git"}, {"version": "998f70d1806bb718a7565f350283e4a79c8cbb4b", "lessThan": "8391ee06d08845a0a165b5fe679ba326915166b2", "status": "affected", "versionType": "git"}, {"version": "998f70d1806bb718a7565f350283e4a79c8cbb4b", "lessThan": "47504742cea7878ebd1bf1491bbed923df6b90b1", "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/mfd/qnap-mcu.c"], "versions": [{"version": "6.14", "status": "affected"}, {"version": "0", "lessThan": "6.14", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.51", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc1", "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": "6.14", "versionEndExcluding": "6.18.51"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.3-rc1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0b6680e306397097a97767447368221fac753809"}, {"url": "https://git.kernel.org/stable/c/8391ee06d08845a0a165b5fe679ba326915166b2"}, {"url": "https://git.kernel.org/stable/c/47504742cea7878ebd1bf1491bbed923df6b90b1"}], "title": "mfd: qnap-mcu: keep the reply buffer alive past a command timeout", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/mfd/qnap-mcu.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "0b6680e306397097a97767447368221fac753809", "status": "affected", "version": "998f70d1806bb718a7565f350283e4a79c8cbb4b", "versionType": "git"}, {"lessThan": "8391ee06d08845a0a165b5fe679ba326915166b2", "status": "affected", "version": "998f70d1806bb718a7565f350283e4a79c8cbb4b", "versionType": "git"}, {"lessThan": "47504742cea7878ebd1bf1491bbed923df6b90b1", "status": "affected", "version": "998f70d1806bb718a7565f350283e4a79c8cbb4b", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/mfd/qnap-mcu.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.14"}, {"lessThan": "6.14", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.51", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3-rc1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmfd: qnap-mcu: keep the reply buffer alive past a command timeout\n\nqnap_mcu_exec() publishes an on-stack buffer to the receive path:\n\n\tunsigned char rx[QNAP_MCU_RX_BUFFER_SIZE];\n\t...\n\treply->data = rx;\n\treply->length = length;\n\nand qnap_mcu_receive_buf() writes into it from the serdev receive path,\nwhich runs out of flush_to_ldisc() and is not serialized against\nqnap_mcu_exec() at all. bus_lock cannot cover it, because qnap_mcu_exec()\nholds that mutex across wait_for_completion_timeout().\n\nOn a timeout qnap_mcu_exec() returns with reply->data still pointing at\nits own frame. A reply that arrives late, or an unsolicited message from\nthe MCU, is then written into a stack frame that has been left, corrupting\nwhatever runs next on that stack. The same applies when qnap_mcu_write()\nfails, since that path returns without touching the reply state either.\n\nMove the receive buffer into struct qnap_mcu. It is 37 bytes and the\nstructure is devm_kzalloc()ed, so it lives as long as the driver, and a\nlate write lands in memory that is still valid and is reinitialized by the\nnext command. bus_lock keeps commands from sharing it.\n\nThis deliberately does not clear reply->data or reply->length on the\ntimeout path. Doing so races with qnap_mcu_receive_buf(), which reads both\nafter its\n\n\tif (!reply->length)\n\t\treturn size;\n\ncheck: clearing reply->data gives a NULL dereference, and clearing\nreply->length alone removes the reply->received == reply->length exit\ncondition, so the copy loop runs until the uart chunk is consumed and\noverruns the buffer. Leaving both set keeps the write bounded by\nreply->length, which qnap_mcu_exec() has already checked against\nsizeof(mcu->rx)."}], "id": "CVE-2026-80975", "lastModified": "2026-09-13T07:17:04.190", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-11T20:19:03.763", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0b6680e306397097a97767447368221fac753809"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/47504742cea7878ebd1bf1491bbed923df6b90b1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8391ee06d08845a0a165b5fe679ba326915166b2"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: qnap-mcu driver memory corruption due to stale stack buffer", "id": "2532227", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532227"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H", "status": "draft"}, "cwe": "CWE-562", "details": ["A flaw was found in the Linux kernel's `qnap-mcu` driver. This vulnerability occurs when the driver processes commands and a reply from the Microcontroller Unit (MCU) arrives after a command has timed out or failed. The driver may write this late or unsolicited message into a memory area that is no longer in use, leading to memory corruption. This can result in system instability or a denial of service."], "name": "CVE-2026-80975", "public_date": "2026-09-11T19:42:37Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-80975\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-80975\nhttps://git.kernel.org/stable/c/0b6680e306397097a97767447368221fac753809\nhttps://git.kernel.org/stable/c/47504742cea7878ebd1bf1491bbed923df6b90b1\nhttps://git.kernel.org/stable/c/8391ee06d08845a0a165b5fe679ba326915166b2"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[998f70d1806bb718a7565f350283e4a79c8cbb4b,0b6680e306397097a97767447368221fac753809)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[998f70d1806bb718a7565f350283e4a79c8cbb4b,8391ee06d08845a0a165b5fe679ba326915166b2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[998f70d1806bb718a7565f350283e4a79c8cbb4b,47504742cea7878ebd1bf1491bbed923df6b90b1)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "6.14"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.14)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.51,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.4,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T02:15:06.471240+00:00", "updated": "2026-09-13T17:00:12.201212+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}