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Critical

QOS.ch Logback vulnerable to Deserialization of Untrusted Data

  • Disclosed: 07.06.2021
  • Updated: 11.10.2026 12:21

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.

Affected software

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PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) ch.qos.logback:logback-classic < 1.2.0 1.2.0
Java / Kotlin (Maven) ch.qos.logback:logback-core < 1.2.0 1.2.0

References

CVSS score 9.8/10
CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE)
CWE-502
Platform
Java / Kotlin (Maven)
Package
ch.qos.logback:logback-classic, ch.qos.logback:logback-core
Disclosed
07.06.2021
Updated
11.10.2026 12:21

Sources and licenses

OSV / GitHub Advisory Database - GHSA-vmfg-rjjm-rjrj - CC BY 4.0

Vulnerability history: ch.qos.logback:logback-core

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (10) in the archive
Total entries
10
First → latest
06.2021 06.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 1
  • High 2
  • Medium 3
  • Low 4

Disclosures per year

Severity:
  1. Logback is vulnerable to an attacker mounting a Denial-Of-Service attack by sending poisoned data
    High · 7.1 CVE-2023-6481 >= 1.4.13, < 1.4.14, >= 1.3.13, < 1.3.14, >= 1.2.12, < 1.2.13 1.4.14, 1.3.14, 1.2.13
  2. logback serialization vulnerability
    High · 7.1 CVE-2023-6378 >= 1.3.0, < 1.3.12, >= 1.4.0, < 1.4.12, < 1.2.13 1.3.12, 1.4.12, 1.2.13
  3. QOS.ch Logback vulnerable to Deserialization of Untrusted Data this entry
    Critical · 9.8 CVE-2017-5929 < 1.2.0 1.2.0

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