CVE-2026-16458 in ocrypto
Summary
by MITRE • 08/13/2026
Padding oracle attack vulnerability in Oberon microsystem AG’s ocrypto library in all versions since 3.0.0 and prior to 4.0.1 allows an attacker to recover plaintexts via timing measurements of RSA PKCS#1 v1.5 decrypt operations.
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Analysis
by VulDB Data Team • 08/13/2026
A padding oracle attack vulnerability exists within the ocrypto library developed by Oberon microsystems AG, affecting all versions from 3.0.0 through 4.0.0. This critical flaw stems from insufficient timing consistency in RSA PKCS#1 v1.5 decrypt operations, where attackers can exploit measurable time differences to infer cryptographic secrets. The vulnerability manifests when the library performs decryption operations without adequate constant-time execution, creating observable timing variations that correlate with successful or failed padding validation checks.
The technical implementation of this vulnerability resides in how the cryptographic library handles RSA decryption processes under PKCS#1 v1.5 padding standards. When an attacker submits maliciously crafted ciphertext to the vulnerable system, the timing variations in response processing reveal information about whether the padding is valid or invalid. This oracle allows for iterative attacks where each timing measurement provides one bit of information about the plaintext, ultimately enabling complete recovery of encrypted data through systematic probing.
This vulnerability directly impacts the confidentiality and integrity of cryptographic communications relying on the affected library version. Attackers can exploit this weakness to decrypt sensitive data without possessing the corresponding private keys, undermining the fundamental security assumptions of RSA encryption. The operational impact extends beyond simple data theft, as compromised encrypted communications may lead to broader system compromise through credential exposure, financial data breaches, or intellectual property theft.
The vulnerability aligns with CWE-310 and CWE-327, specifically addressing weaknesses in cryptographic implementations related to timing side channels and improper encryption padding. From an ATT&CK perspective, this represents a technique for privilege escalation and credential access through cryptanalysis, falling under the category of 'Cryptographic Attack' with potential lateral movement implications when attackers can decrypt communications between systems. Organizations using vulnerable versions should immediately upgrade to ocrypto library version 4.0.1 or later, which implements proper constant-time execution patterns to eliminate timing variations. Additionally, system administrators should monitor network traffic for signs of exploitation attempts and consider implementing additional cryptographic security controls such as secure key management practices and regular security assessments.
The remediation strategy involves not only patching the specific library version but also establishing comprehensive monitoring procedures to detect potential exploitation attempts. Organizations should conduct thorough inventory checks to identify all systems utilizing the vulnerable library, implement network segmentation to limit attack surface, and establish incident response protocols specifically addressing cryptographic vulnerabilities. Security teams must also consider the broader implications of this vulnerability within their infrastructure, as many applications may rely on similar cryptographic libraries or implementations that could present analogous weaknesses requiring similar remediation approaches.