CVE-2026-59321: Shared JSR-223 ScriptEngine evaluated concurrently without THREADING check

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-27 · updated 2026-08-31
Weakness: CWE-362

Description

A single ScriptEngine instance is reused for every message on a script-backed channel. For JSR-223 engines that report THREADING=null (not thread-safe, e.g. the Kotlin kts engine), concurrent message processing can corrupt engine-internal state, potentially leaking one message's payload/headers bindings into another message's script evaluation or throwing spurious exceptions. Spring Integration 7.1.0 Spring Integration 7.0.0 - 7.0.5 Spring Integration 6.5.0 - 6.5.10 Spring Integration 6.4.0 - 6.4.12 Spring Integration 5.5.21 and earlier

Affected products

Spring Integration: through 5.5.21; from 6.4.0 through 6.4.12; from 6.5.0 through 6.5.10; from 7.0.0 before 7.0.5.1; from 7.1.0 before 7.1.0.1 — fixed in 7.0.5.1, 7.1.0.1
Spring Integration: from 7.0.0 through 7.0.5; from 6.5.0 through 6.5.10; from 6.4.0 through 6.4.12; through 5.5.21; 7.1.0

How to fix

Upgrade to a fixed version: Spring Integration 7.0.5.1, 7.1.0.1. Check the vendor advisory for mitigations.

References

https://spring.io/security/cve-2026-59321

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