CVE-2026-81706 in Openssl Encrypt
Summary
by MITRE • 08/27/2026
openssl_encrypt before 1.4.9 fails to prevent namespace collisions between own identities and contacts in IdentityStore, allowing attackers to create shadowed contact entries invisible until the corresponding own identity is deleted. When the own identity is deleted, the shadowed contact becomes visible and resolves to the attacker's keys, enabling silent key substitution for encrypted files.
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Analysis
by VulDB Data Team • 08/27/2026
The vulnerability identified involves a critical flaw in the namespace management logic within the IdentityStore component of OpenSSL Encrypt prior to version 1.4.9. This defect allows for a sophisticated form of identity spoofing and data integrity compromise by exploiting how unique identifiers are resolved during cryptographic operations. The core technical issue stems from an insufficient separation between namespaces reserved for local user identities and those used for external contacts or peers. In secure messaging applications, the IdentityStore is responsible for mapping human-readable names or addresses to their corresponding public keys. When a system fails to strictly enforce namespace isolation, it creates an opportunity for attackers to register contact entries that share identifiers with existing own identities of legitimate users. This architectural oversight means that the lookup mechanism does not prioritize local identity records over external ones when resolving ambiguous references, leading directly to potential shadowing attacks where malicious entities can masquerade as trusted parties.
From a technical perspective, this flaw enables an attacker to create shadowed contact entries that remain invisible during normal operation because the system prioritizes the user's own identity record for resolution. The vulnerability is particularly insidious because it does not trigger immediate alerts or errors; instead, it operates silently in the background. An attacker can register a public key under an identifier that matches one of the victim’s known identities. As long as the victim’s corresponding local identity entry exists and takes precedence in the lookup table, the malicious registration remains dormant. However, if the user deletes their own identity record from the store for any reason, such as account cleanup or migration, the system falls back to resolving that identifier through external sources. At this point, the shadowed contact becomes visible and resolves to the attacker’s public key rather than a legitimate peer’s key. This mechanism effectively allows for silent key substitution without requiring social engineering or direct interaction with the victim at the moment of compromise.
The operational impact of this vulnerability is severe, as it directly undermines the confidentiality and integrity guarantees provided by end-to-end encryption. When an encrypted file or message is processed after the own identity has been deleted, the system will use the attacker’s public key for verification or decryption processes depending on the specific protocol flow. If the attacker controls the private key corresponding to the shadowed public key, they can decrypt sensitive data that was intended only for the legitimate recipient. Furthermore, in scenarios involving message authentication codes or digital signatures, the victim might inadvertently verify a signature using the wrong trust anchor, potentially accepting maliciously crafted content as authentic. This breaks the fundamental assumption of identity binding in cryptographic protocols, allowing man-in-the-middle attacks to succeed even when users believe they are communicating with verified contacts. The risk is amplified because the compromise occurs after data has been encrypted or signed under the illusion of security, making detection difficult without rigorous audit logs that track key resolution events.
This vulnerability aligns closely with CWE-284 Improper Access Control and CWE-697 Incorrect Comparison During Critical Execution, as it involves a failure to correctly distinguish between different classes of entities within a shared namespace. In the context of the MITRE ATT&CK framework, this behavior is indicative of T1553 Subvert Trust Controls, where an attacker manipulates trust mechanisms like certificate or key stores to bypass security checks. It also relates to T1078 Valid Accounts if the shadowed identity allows access to resources protected by that specific cryptographic identity. To mitigate these risks, developers must implement strict namespace isolation policies within the IdentityStore. This includes ensuring that local identities always take precedence over external registrations and implementing unique constraints that prevent duplicate identifiers across different trust domains. Additionally, systems should employ explicit validation steps when resolving keys for sensitive operations, verifying that the resolved key matches an expected set of trusted peers rather than relying solely on identifier matching. Regular audits of identity stores and clear user notifications regarding changes to stored identities can further reduce the window of opportunity for such attacks.