CVE-2024-23218 is a cryptographic vulnerability identified in Apple iOS and iPadOS, specifically targeting the legacy RSA PKCS#1 v1.5 encryption scheme. The flaw is a timing side-channel issue where the cryptographic functions do not consistently execute in constant time, allowing an attacker to infer information about the plaintext by measuring the time taken to decrypt ciphertexts. This side-channel leakage can enable an attacker to decrypt RSA-encrypted messages without possessing the private key, undermining the confidentiality of communications or stored data encrypted with this legacy scheme. The vulnerability affects multiple Apple operating systems, including iOS, iPadOS, macOS Sonoma, watchOS, and tvOS, with fixes released in versions 17.3 and 14.3 respectively. The CVSS 3.1 base score is 5.9, reflecting medium severity, with an attack vector of network (remote attacker), high attack complexity, no privileges required, no user interaction, and high impact on confidentiality but no impact on integrity or availability. The root cause is the failure to implement constant-time cryptographic operations for RSA PKCS#1 v1.5 decryption, a known best practice to prevent timing attacks. While modern cryptographic standards have moved away from PKCS#1 v1.5 due to its known weaknesses, legacy systems and applications may still rely on it, increasing the risk surface. No public exploits have been reported yet, but the vulnerability's existence necessitates prompt patching and review of cryptographic practices.

For European organizations, the primary impact of CVE-2024-23218 is the potential compromise of confidentiality for data encrypted using legacy RSA PKCS#1 v1.5 on affected Apple devices. This could include sensitive communications, authentication tokens, or stored encrypted data. Organizations in sectors such as finance, healthcare, government, and critical infrastructure that rely on Apple devices for secure communications or data handling are at heightened risk. The vulnerability does not affect data integrity or availability directly but could facilitate further attacks if attackers gain decrypted sensitive information. Since the attack requires network access but no privileges or user interaction, remote exploitation is feasible, increasing the threat surface. The medium severity rating suggests a moderate but non-trivial risk, especially where legacy cryptographic protocols remain in use. Failure to patch could lead to data breaches, loss of trust, and regulatory non-compliance under GDPR and other data protection laws. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the potential for future exploitation.

European organizations should immediately ensure all Apple devices are updated to iOS 17.3, iPadOS 17.3, macOS Sonoma 14.3, watchOS 10.3, and tvOS 17.3 or later to apply the patch that enforces constant-time cryptographic operations. Beyond patching, organizations should audit their cryptographic usage to identify and phase out legacy RSA PKCS#1 v1.5 encryption in favor of modern, secure schemes such as RSA-PSS or elliptic curve cryptography (ECC). Network-level protections such as intrusion detection systems (IDS) and anomaly detection can help identify unusual timing or traffic patterns that might indicate exploitation attempts. Organizations should also review and tighten access controls to limit exposure of cryptographic operations to untrusted networks. For critical systems, consider implementing hardware security modules (HSMs) or secure enclaves that enforce constant-time cryptographic operations. Finally, conduct employee training to raise awareness about timely patching and cryptographic hygiene, and maintain an incident response plan to address potential data breaches stemming from cryptographic vulnerabilities.