matrix-org matrix-rust-sdk up to 0.16.x Olm Decryption improper authentication

Summaryinfo

A vulnerability identified as problematic has been detected in matrix-org matrix-rust-sdk up to 0.16.x. Affected by this vulnerability is an unknown functionality of the component Olm Decryption. The manipulation leads to improper authentication. This vulnerability is uniquely identified as CVE-2026-45056. The attack is possible to be carried out remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in matrix-org matrix-rust-sdk up to 0.16.x. It has been rated as problematic. This issue affects some unknown functionality of the component Olm Decryption. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is integrity. The summary by CVE is:

matrix-sdk-crypto is a no-network-IO implementation of a state machine that handles end-to-end encryption for Matrix clients. Starting in version 0.12.0 and prior to version 0.17.0, the matrix-sdk-crypto crate was missing a check for the user ID when decrypting an Olm-encrypted event containing the `sender_device_keys` property. This could be exploited to forge an encrypted to-device event, but only if the attacker colludes with the homeserver operator. This issue is fixed in matrix-sdk-crypto 0.17.0. There are no known workarounds for the issue.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-45056 since 05/08/2026. The exploitation is known to be easy. The attack may be initiated remotely. Additional levels of successful authentication are required for exploitation. Neither technical details nor an exploit are publicly available.

Upgrading to version 0.17.0 eliminates this vulnerability.

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Productinfo

Vendor

• matrix-org

Name

• matrix-rust-sdk

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16

Website

• Product: https://github.com/matrix-org/matrix-rust-sdk/

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