In JetBrains Ktor before 2.3.5 default configuration of ContentNegotiation with XML format was vulnerable to XXE

JetBrains Ktor framework before 1.2.0-rc does not sanitize the username provided by the user for the LDAP protocol, leading to command injection.

In JetBrains Ktor before 2.3.5 server certificates were not verified

SHA1 implementation in JetBrains Ktor Native 2.0.0 was returning the same value. The issue was fixed in Ktor version 2.0.1.

JetBrains Ktor framework (created using the Kotlin IDE template) versions before 1.1.0 were resolving artifacts using an http connection during the build process, potentially allowing an MITM attack. This issue was fixed in Kotlin plugin version 1.3.30.

In JetBrains Ktor before 1.6.4, nonce verification during the OAuth2 authentication process is implemented improperly.

In JetBrains Ktor before 2.3.0 path traversal in the resolveResource method was possible

In JetBrains Ktor before 1.4.1, HTTP request smuggling was possible.

In JetBrains Ktor before 2.1.0 the wrong authentication provider could be selected in some cases

In Ktor through 1.2.6, the client resends data from the HTTP Authorization header to a redirect location.

JetBrains Ktor before 2.1.0 was vulnerable to the Reflect File Download attack

JetBrains Ktor framework before version 1.2.6 was vulnerable to HTTP Response Splitting.

Improper caching in JetBrains Ktor before 3.0.0 in the HttpCache Plugin could lead to response information disclosure.

In JetBrains Ktor before 1.4.2, weak cipher suites were enabled by default.

In JetBrains Ktor before 1.4.3, HTTP Request Smuggling was possible.

UserHashedTableAuth in JetBrains Ktor framework before 1.2.0-rc uses a One-Way Hash with a Predictable Salt for storing user credentials.

In JetBrains Ktor before 1.5.0, a birthday attack on SessionStorage key was possible.

In JetBrains Ktor Native before version 2.0.0 random values used for nonce generation weren't using SecureRandom implementations