CVE-2026-9828 – Logback deserialization whitelist bypass for java.lang and java.util

CVE ID :CVE-2026-9828

Published : May 28, 2026, 2:16 p.m. | 15 minutes ago

Description :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.

Severity: 1.2 | LOW

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