CVE-2023-50386: Apache Solr ConfigSet backup allows upload and loading of executable code

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 18 September 2026. Confidence: high.

high priorityCVSS 8.8 and a very high EPSS score indicate serious, remotely reachable code execution risk, though exploitation requires API privileges and is not known to be actively exploited.

What it is

Apache Solr ConfigSets accepted Java jar and class files uploaded through the ConfigSets API, and the Backup API using the default LocalFileSystemRepository could write those files into directories Solr uses for its ClassPath/ClassLoaders. Once there, the code becomes available to any ConfigSet, trusted or untrusted, turning a backup operation into a code deployment path. Affected versions are 6.0.0 through 8.11.2 and 9.0.0 before 9.4.1.

Impact

An attacker with the ability to use the ConfigSets and Backup APIs can place attacker-controlled Java libraries where Solr will load them, leading to code execution in the Solr process with high impact to confidentiality, integrity and availability.

Attack surface

Reached over the network through the Solr ConfigSets and Backup APIs; the CVSS vector indicates low privileges are required and no user interaction. When authorization is enabled, the flaw is limited to extending Backup permissions with the ability to add libraries.

Exploitation

Not listed in CISA KEV and no ransomware usage is documented; EPSS is very high at 0.837 probability (99.7th percentile), and references are only the vendor advisory and mailing list, with no public exploit tag.

What to do

• Upgrade to Apache Solr 8.11.3 or 9.4.1, which block uploads of ClassLoader-executable files to ConfigSets and restrict Backup API writes to ClassLoader directories.
• Enable Solr authorization and restrict ConfigSets and Backup API permissions to the minimum set of trusted administrators.
• Configure backups to write to a directory outside Solr's ClassPath and ClassLoader paths.
• Audit existing ConfigSets and backup directories for unexpected jar or class files and remove any that are not required.

Detection

• Monitor Solr logs and API access logs for ConfigSets uploads containing .jar or .class files.
• Alert on Backup API calls that write into directories used by Solr ClassPath or ClassLoaders.
• Scan Solr configSet and backup directories for newly appearing jar or class files and compare against a known-good baseline.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.