CVE-2025-66038

/* * PoC Concept for CVE-2025-66038 * This C code demonstrates the condition that triggers the vulnerability. */ #include <stdio.h> #include <stdlib.h> // Mocking the vulnerable function signature int sc_compacttlv_find_tag_vulnerable(const unsigned char *buf, size_t buflen, unsigned int tag_in, const unsigned char **buf_out, size_t *len_out) { // Simplified vulnerable logic if (buflen < 1) return -1; unsigned char first_byte = buf[0]; unsigned char current_tag = first_byte >> 4; unsigned char current_len = first_byte & 0x0F; if (current_tag == tag_in) { // VULNERABILITY: Does not check if current_len fits in (buflen - 1) *buf_out = buf + 1; *len_out = current_len; return 0; // Success } return -1; // Not found } int main() { // Malicious input: Tag 0x0, Length 10 (0xA), but buffer size is only 1 byte unsigned char malicious_buffer[] = {0x0A}; const unsigned char *result_ptr = NULL; size_t result_len = 0; printf("Attempting to parse malicious buffer...\n"); int ret = sc_compacttlv_find_tag_vulnerable(malicious_buffer, sizeof(malicious_buffer), 0x00, &result_ptr, &result_len); if (ret == 0) { printf("Tag found. Pointer: %p, Length: %zu\n", result_ptr, result_len); // The following access would cause an out-of-bounds read // printf("Value: %x\n", *result_ptr); printf("Out-of-bounds read prevented in this demo.\n"); } return 0; }

{"cve": {"id": "CVE-2025-66038", "sourceIdentifier": "[email protected]", "published": "2026-03-30T18:16:18.177", "lastModified": "2026-04-01T17:40:36.183", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenSC is an open source smart card tools and middleware. Prior to version 0.27.0, sc_compacttlv_find_tag searches a compact-TLV buffer for a given tag. In compact-TLV, a single byte encodes the tag (high nibble) and value length (low nibble). With a 1-byte buffer {0x0A}, the encoded element claims tag=0 and length=10 but no value bytes follow. Calling sc_compacttlv_find_tag with search tag 0x00 returns a pointer equal to buf+1 and outlen=10 without verifying that the claimed value length fits within the remaining buffer. In cases where the sc_compacttlv_find_tag is provided untrusted data (such as being read from cards/files), attackers may be able to influence it to return out-of-bounds pointers leading to downstream memory corruption when subsequent code tries to dereference the pointer. This issue has been patched in version 0.27.0."}, {"lang": "es", "value": "OpenSC es un conjunto de herramientas y middleware de código abierto para tarjetas inteligentes. Antes de la versión 0.27.0, sc_compacttlv_find_tag busca una etiqueta dada en un búfer compact-TLV. En compact-TLV, un solo byte codifica la etiqueta (nibble superior) y la longitud del valor (nibble inferior). Con un búfer de 1 byte {0x0A}, el elemento codificado declara etiqueta=0 y longitud=10 pero no le siguen bytes de valor. Llamar a sc_compacttlv_find_tag con la etiqueta de búsqueda 0x00 devuelve un puntero igual a buf+1 y outlen=10 sin verificar que la longitud de valor declarada cabe dentro del búfer restante. En los casos en que a sc_compacttlv_find_tag se le proporcionan datos no confiables (como los leídos de tarjetas/archivos), los atacantes pueden influir en ella para que devuelva punteros fuera de los límites, lo que lleva a una corrupción de memoria posterior cuando el código subsiguiente intenta desreferenciar el puntero. Este problema ha sido corregido en la versión 0.27.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L", "baseScore": 3.9, "baseSeverity": "LOW", "attackVector": "PHYSICAL", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 0.5, "impactScore": 3.4}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 6.8, "baseSeverity": "MEDIUM", "attackVector": "PHYSICAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 0.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-126"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:opensc_project:opensc:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.27.0", "matchCriteriaId": "D890677F-5379-4587-B8E7-D38B02AD525A"}]}]}], "references": [{"url": "https://github.com/OpenSC/OpenSC/commit/6db171bcb6fd7cb3b51098fefbb3b28e44f0a79c", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/OpenSC/OpenSC/security/advisories/GHSA-72x5-fwjx-2459", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/OpenSC/OpenSC/wiki/CVE-2025-66038", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}