Threat actors started exploiting an unpatched zero-day vulnerability in GeoServer hours after it was publicly disclosed, attack surface management firm WatchTowr says.

The security defect, described as an SQL injection issue that could be exploited to achieve remote code execution (RCE), was disclosed on Wednesday by a security researcher named q1uf3ng.

According to the researcher’s post on X, the flaw affects GeoServer’s jsonArrayContains function, a filter expression for querying JSON array fields to check if they contain specific values. It can be used with PostGIS and Oracle JDBC data stores.

The SQL injection is likely caused by user-supplied arguments being improperly sanitized before they are encoded into database queries, which, under certain configurations, leads to RCE.

According to WatchTowr, threat actors started exploiting the unpatched zero-day vulnerability shortly after it became public.

“Within hours of public disclosure, we began observing exploitation attempts and have since recorded hundreds of attempts originating from a small number of source IP addresses. Yet another example of how quickly attackers move once a vulnerability enters the public domain,” WatchTowr’s Jake Knott said.

Threat actors have been targeting the security defect to probe vulnerable systems, but no follow-up activity has been observed.

“However, this is unlikely to remain the case for long: GeoServer has a track record of being targeted and exploited at scale, with multiple vulnerabilities listed in CISA’s Known Exploited Vulnerabilities catalog,” Knott said.

“With no patch currently available and exploitation already underway, organizations running GeoServer should take this vulnerability seriously and, where possible, identify exposed instances, restrict public access, and monitor for a vendor fix,” he added.

A popular open source platform for sharing and processing geospatial data, GeoServer is used across government, agriculture, telecoms, transit, and other industries.

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