CVE-2026-9828: QOS.CH Sarl logback logback-core has a deserialization of untrusted data vulnerability

May 28, 2026 (updated July 2, 2026)

Deserialization of untrusted data vulnerability in QOS.CH Sarl logback logback-core (HardenedObjectInputStream (logback-core) modules) allows Object Injection albeit heavily restricted.

More precisely, an attacker able to influence serialized data sent to SimpleSocketServer or SimpleSSLSocketServer can instantiate objects from classes in the java.lang and java.util packages that are not explicitly blocked.

Although deserialization is heavily restricted by HardenedObjectInputStream and no practical way to achieve remote code execution or significant privilege escalation has been identified, this issue constitutes a bypass of the intended security restrictions.

This issue affects logback: through 1.5.32 inclusive.

References

Code Behaviors & Features

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