CVE-2026-43055

/* * Conceptual PoC for CVE-2026-43055 * This code demonstrates the logic flaw leading to the vulnerability. * It simulates the kernel behavior where uninitialized memory causes a check failure. */ #include <stdio.h> #include <stdlib.h> #define MAX_WRITE_STREAMS 10 struct iocb { int ki_write_stream; }; struct aio_cmd { struct iocb iocb; }; // Simulating the vulnerable allocation logic (not zeroing memory) struct aio_cmd* vulnerable_alloc() { // In real kernel: kmalloc instead of kzalloc_flex return (struct aio_cmd*)malloc(sizeof(struct aio_cmd)); } // Simulating the fixed allocation logic struct aio_cmd* fixed_alloc() { struct aio_cmd* cmd = (struct aio_cmd*)malloc(sizeof(struct aio_cmd)); if (cmd) { cmd->iocb.ki_write_stream = 0; // Explicit initialization } return cmd; } int execute_write(struct aio_cmd* cmd) { // Block layer check if (cmd->iocb.ki_write_stream > MAX_WRITE_STREAMS) { printf("[!] Write Failed: Invalid stream ID %d\n", cmd->iocb.ki_write_stream); return -1; } printf("[+] Write Success\n"); return 0; } int main() { printf("--- Testing Vulnerable Scenario ---\n"); struct aio_cmd* cmd_vuln = vulnerable_alloc(); // Note: ki_write_stream is uninitialized here, might contain garbage > MAX_WRITE_STREAMS execute_write(cmd_vuln); free(cmd_vuln); printf("\n--- Testing Fixed Scenario ---\n"); struct aio_cmd* cmd_fixed = fixed_alloc(); execute_write(cmd_fixed); free(cmd_fixed); return 0; }

{"cve": {"id": "CVE-2026-43055", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:52.040", "lastModified": "2026-05-07T18:58:41.247", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: target: file: Use kzalloc_flex for aio_cmd\n\nThe target_core_file doesn't initialize the aio_cmd->iocb for the\nki_write_stream. When a write command fd_execute_rw_aio() is executed,\nwe may get a bogus ki_write_stream value, causing unintended write\nfailure status when checking iocb->ki_write_stream > max_write_streams\nin the block device.\n\nLet's just use kzalloc_flex when allocating the aio_cmd and let\nki_write_stream=0 to fix this issue."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "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": "6.16", "versionEndExcluding": "6.18.22", "matchCriteriaId": "B376ADEA-99DD-4C34-B0B2-7362FBE63A29"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.12", "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36"}, {"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"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/01f784fc9d0ab2a6dac45ee443620e517cb2a19b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4eaff1728d0e69b95933412241bbccf4f797dba8", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/ce54802fe6bb78eb0feffc66fed6a45d41ffc3ab", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}