JetBrains Kotlin: Unsafe Deserialization in Kotlin Build Cache Enables Code Execution

CRITICAL 9.8CVE-2026-53914 · GHSA-r937-wjx7-w2jp · Published 26/06/2026 · updated 25/10/2026

In short

CVE-2026-53914 is a CRITICAL (CVSS 9.8) vulnerability affecting org.jetbrains.kotlin:kotlin-gradle-plugin, kotlin (jetbrains).
Chance of exploitation in the next 30 days (EPSS): 0.33%, higher than 26.6% of all vulnerabilities.
Fix: update to 2.4.20-Beta1, 2.4.20 or later.

Package	Affected versions	Patched versions
org.jetbrains.kotlin:kotlin-gradle-plugin Maven	`< 2.4.20-Beta1`	`2.4.20-Beta1`
kotlin jetbrains	`< 2.4.20`	`2.4.20`

In JetBrains Kotlin before 2.4.20 code execution was possible via unsafe deserialization in the build cache metadata

NVD description

In JetBrains Kotlin before 2.4.20 code execution was possible via unsafe deserialization in the build cache metadata

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