CVE-2026-31790 is a high-severity vulnerability affecting OpenSSL versions that utilize RSASVE key encapsulation. This vulnerability allows applications to inadvertently send contents of an uninitialized memory buffer to a malicious peer, leading to sensitive data leakage. The severity of this issue is underscored by its CVSS score of 7.5, indicating a high level of risk to organizations that rely on OpenSSL for secure communications.
The vulnerability arises from the RSA_public_encrypt() function, which fails to adequately check its return value. When the function fails, it may still return success, allowing the output length to be set and potentially exposing stale or uninitialized data to an attacker. This risk is compounded when applications use EVP_PKEY_encapsulate() with an invalid RSA public key without validation.
Organizations should prioritize patching immediately. The uninitialized buffer could contain sensitive data from previous executions, making it critical for affected applications to implement proper key validation to prevent this leakage.
To mitigate this vulnerability, it is recommended to call EVP_PKEY_public_check() or EVP_PKEY_public_check_quick() before EVP_PKEY_encapsulate(). The OpenSSL FIPS modules 3.0 through 3.6 are also impacted, necessitating swift remediation.
Vulnerability Details
The official description states that applications using RSASVE key encapsulation can inadvertently leak sensitive data due to uninitialized buffers. The CVSS score of 7.5 reflects the high confidentiality impact, while integrity and availability impacts are noted as none. The vulnerability affects all versions of OpenSSL from 3.0.0 to below 3.0.20, 3.3.0 to below 3.3.7, 3.4.0 to below 3.4.5, 3.5.0 to below 3.5.6, and 3.6.0 to below 3.6.2.
The vulnerability falls under CWE-754, indicating the potential for unintended exposure of sensitive information. It is crucial for organizations using vulnerable versions to assess their systems and apply necessary patches or workarounds.
Technical Analysis
The root cause of this vulnerability lies in the failure of RSA_public_encrypt() to validate its return value properly. When RSA encryption fails, the encapsulation may still be reported as successful without appropriate validation, allowing uninitialized memory to be exposed. This scenario presents a low attack complexity as no privileges or user interaction are required for exploitation.
Attackers may leverage this vulnerability through a network vector, making it particularly dangerous. The confidentiality impact is rated high, as sensitive data may be disclosed, while both integrity and availability impacts are rated none. As a result, organizations must not only patch affected systems but also implement secure coding practices to validate inputs and outputs.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2026-31790 is significant, especially for applications that handle sensitive data. The potential for data leakage to attackers poses a serious threat, particularly in environments where OpenSSL is used to establish secure communication channels.
Organizations should assess the potential blast radius of this vulnerability across their infrastructures, especially in cases where multiple applications utilize the same OpenSSL libraries. Given the high CVSS score and the fact that this vulnerability is not included in the KEV catalog, it is vital for organizations to prioritize patching within their security operations.
The urgency for organizations to remediate this vulnerability is high, and they should schedule remediation as part of their next patch cycle. Continuous monitoring and validation of security practices must also be emphasized to prevent similar vulnerabilities from being introduced in the future.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of OpenSSL include all versions from 3.0.0 to below 3.0.20, 3.3.0 to below 3.3.7, 3.4.0 to below 3.4.5, 3.5.0 to below 3.5.6, and 3.6.0 to below 3.6.2. Organizations using these versions should take immediate action to patch or upgrade their systems.
Mitigation & Remediation
To mitigate CVE-2026-31790, organizations should promptly apply the relevant patches provided by OpenSSL. If a patch is not immediately available, a temporary workaround involves calling EVP_PKEY_public_check() or EVP_PKEY_public_check_quick() before EVP_PKEY_encapsulate(). This will help ensure that the public key is valid before proceeding with the encapsulation process.
Organizations can further enhance their security posture by implementing network controls, such as restricting access to critical systems and monitoring for unusual activities. Continuous monitoring of application logs for any anomalies is also recommended to detect potential exploitation attempts.
Penetration testing can also be employed to validate the effectiveness of remediation efforts.
Detection Guidance
Organizations should monitor the following indicators to detect potential exploitation of CVE-2026-31790:
1. Log entries that indicate invalid RSA public key usage.
2. Behavioral anomalies in applications that utilize OpenSSL for encryption.
3. Network signatures that may indicate unauthorized access or attempts to exploit the vulnerability.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2026-31790 is evident as organizations increasingly depend on OpenSSL for secure transactions. This vulnerability underscores the importance of rigorous validation mechanisms in cryptographic implementations.
This incident may signify a pattern where cryptographic libraries face scrutiny due to their critical roles in data security. Security teams are advised to implement strict code reviews and testing to prevent similar vulnerabilities in future releases.
For organizations, a strategic takeaway would be to integrate security testing into the development lifecycle, ensuring vulnerabilities are identified and mitigated before deployment. Regular training and awareness initiatives can also empower developers to adhere to secure coding practices.
Security testing best practices should be a core component of any security strategy moving forward.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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