Summary
QOS.ch Logback vulnerable to Deserialization of Untrusted Data
QOS.ch Logback before 1.2.0 has a serialization vulnerability affecting the SocketServer and ServerSocketReceiver components. The RemoteStreamAppenderClient class in logback-classic and the SocketNode classes in logback-classic and logback-access allow data to be deserialized over a Java Socket, via an ObjectInputStream, without validating the data beforehand. When data is received from the Socket, to be logged, it is deserialized into Java objects.An attacker can exploit this vulnerability by sending malicious, serialized Java objects over the connection to the Socket, which may result in execution of arbitrary code when those objects are deserialized. Note that although logback-core is implicated by the Logback project here, the Sonatype Security Research team discovered that the vulnerability is actually present in the logback-classic and logback-access components. Versions prior to 1.2.0 are vulnerable, as stated in the advisory.
Impact
Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.
CVE-2017-5929 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.2.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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ch.qos.logback:logback-classic to 1.2.0 or later; ch.qos.logback:logback-core to 1.2.0 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2017-5929? CVE-2017-5929 is a critical-severity insecure deserialization vulnerability in ch.qos.logback:logback-classic (maven), affecting versions < 1.2.0. It is fixed in 1.2.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
- How severe is CVE-2017-5929? CVE-2017-5929 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2017-5929?
ch.qos.logback:logback-classic(maven) (versions < 1.2.0)ch.qos.logback:logback-core(maven) (versions < 1.2.0)
- Is there a fix for CVE-2017-5929? Yes. CVE-2017-5929 is fixed in 1.2.0. Upgrade to this version or later.
- Is CVE-2017-5929 exploitable, and should I be worried? Whether CVE-2017-5929 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2017-5929 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2017-5929?
- Upgrade
ch.qos.logback:logback-classicto 1.2.0 or later - Upgrade
ch.qos.logback:logback-coreto 1.2.0 or later
- Upgrade