CVE-2026-9828: Logback deserialization whitelist bypass for java.lang and java.util
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
logbackto a version that resolves this vulnerability.Fixed in 1.5.33
Event History
Frequently Asked Questions
What is the severity of CVE-2026-9828?
The severity of CVE-2026-9828 is rated as low with a CVSS score of 4.0.
What does CVE-2026-9828 exploit?
CVE-2026-9828 exploits a deserialization vulnerability in QOS.CH logback allowing object injection.
How do I fix CVE-2026-9828?
To fix CVE-2026-9828, upgrade to logback version 1.5.33.
What components are affected by CVE-2026-9828?
CVE-2026-9828 affects the logback-core modules of QOS.CH logback.
What is the potential impact of CVE-2026-9828?
The potential impact of CVE-2026-9828 includes the possibility for attackers to inject malicious objects into serialized data.