Legion of the Bouncy Castle bc-csharp up to 2.6.x IesEngine missing encryption

Summaryinfo

A vulnerability classified as problematic was found in Legion of the Bouncy Castle bc-csharp up to 2.6.x. Affected is an unknown function of the component IesEngine. Executing a manipulation can lead to missing encryption. This vulnerability is tracked as CVE-2026-16001. The attack can be launched remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Legion of the Bouncy Castle bc-csharp up to 2.6.x. It has been declared as problematic. This vulnerability affects an unknown function of the component IesEngine. The manipulation with an unknown input leads to a missing encryption vulnerability. The CWE definition for the vulnerability is CWE-311. The product does not encrypt sensitive or critical information before storage or transmission. As an impact it is known to affect confidentiality. CVE summarizes:

Exposure of the message authentication key through the encryption keystream in the stream mode of IesEngine (an IesEngine constructed without a block cipher) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who has observed one encrypted message with known plaintext to forge shorter messages of their choosing that the recipient accepts as authentic, via a crafted ciphertext and MAC tag, because the MAC key was taken from the key derivation output directly after a keystream as long as the message, while the derivation input depends only on the static key pair and fixed parameters. The keystream revealed by that one message therefore contains the MAC key for every sufficiently shorter message.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-16001 since 07/17/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1600.

Upgrading to version 2.7.0 eliminates this vulnerability.

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Productinfo

Vendor

• Legion of the Bouncy Castle

Name

• bc-csharp

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6

CPE 2.3info

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CPE 2.2info

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