CVE-2026-23558

#include <xenctrl.h> #include <pthread.h> #include <stdio.h> // Conceptual Proof of Concept for CVE-2026-23558 // This code simulates the race condition between grant table version change // and status page mapping in a Xen guest. void* change_grant_version(void* arg) { // Attempt to switch grant table version from v2 to v1 // System call: GNTTABOP_set_version printf("[+] Thread 1: Switching grant table version to v1...\n"); // xc_gnttab_set_version(xc_handle, 1); return NULL; } void* map_status_page(void* arg) { // Attempt to map status pages via XENMEM_add_to_physmap // This must run in parallel with the version change printf("[+] Thread 2: Mapping status pages via add_to_physmap...\n"); // xc_domain_memory_map(xc_handle, ...); return NULL; } int main() { pthread_t t1, t2; printf("[*] Starting PoC for CVE-2026-23558...\n"); // Create threads to trigger the race window pthread_create(&t1, NULL, change_grant_version, NULL); pthread_create(&t2, NULL, map_status_page, NULL); pthread_join(t1, NULL); pthread_join(t2, NULL); printf("[*] Exploit attempt finished.\n"); return 0; }

{"cve": {"id": "CVE-2026-23558", "sourceIdentifier": "[email protected]", "published": "2026-05-19T14:16:38.960", "lastModified": "2026-05-19T18:55:19.793", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "The adjustments made for XSA-379 as well as those subsequently becoming\nXSA-387 still left a race window, when a HVM or PVH guest does a grant\ntable version change from v2 to v1 in parallel with mapping the status\npage(s) via XENMEM_add_to_physmap. Some of the status pages may then be\nfreed while mappings of them would still be inserted into the guest's\nsecondary (P2M) page tables."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.1, "impactScore": 6.0}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-362"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.0.0", "matchCriteriaId": "3E095C1C-0DC6-4380-9333-477B13273E9E"}]}]}], "references": [{"url": "https://xenbits.xenproject.org/xsa/advisory-486.html", "source": "[email protected]", "tags": ["Mitigation", "Patch", "Vendor Advisory"]}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/28/13", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List", "Mitigation", "Patch", "Third Party Advisory"]}, {"url": "http://xenbits.xen.org/xsa/advisory-486.html", "source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mitigation", "Patch", "Vendor Advisory"]}]}}