A lately disclosed safety flaw impacting Apache Tomcat has come underneath energetic exploitation within the wild following the discharge of a public proof-of-concept (PoC) a mere 30 hours after public disclosure.
The vulnerability, tracked as CVE-2025-24813, impacts the under variations –
- Apache Tomcat 11.0.0-M1 to 11.0.2
- Apache Tomcat 10.1.0-M1 to 10.1.34
- Apache Tomcat 9.0.0-M1 to 9.0.98
It issues a case of distant code execution or info disclosure when particular situations are met –
- Writes enabled for the default servlet (disabled by default)
- Assist for partial PUT (enabled by default)
- A goal URL for safety delicate uploads that could be a sub-directory of a goal URL for public uploads
- Attacker information of the names of safety delicate recordsdata being uploaded
- The safety delicate recordsdata are additionally being uploaded through partial PUT
Profitable exploitation might allow a malicious person to view safety delicate recordsdata or inject arbitrary content material into these recordsdata by way of a PUT request.
Moreover, an attacker might obtain distant code execution if all the next situations are true –
- Writes enabled for the default servlet (disabled by default)
- Assist for partial PUT (enabled by default)
- Utility was utilizing Tomcat’s file primarily based session persistence with the default storage location
- Utility included a library which may be leveraged in a deserialization assault
In an advisory launched final week, the undertaking maintainers mentioned the vulnerability has been resolved in Tomcat variations 9.0.99, 10.1.35, and 11.0.3.
However in a regarding twist, the vulnerability is already seeing exploitation makes an attempt within the wild, per Wallarm.
“This assault leverages Tomcat’s default session persistence mechanism together with its assist for partial PUT requests,” the corporate mentioned.
“The exploit works in two steps: The attacker uploads a serialized Java session file through PUT request. The attacker triggers deserialization by referencing the malicious session ID in a GET request.”
Put in a different way, the assaults entail sending a PUT request containing a Base64-encoded serialized Java payload that is written to Tomcat’s session storage listing, which subsequently will get executed throughout deserialization by sending a GET request with the JSESSIONID pointing to the malicious session.
Wallarm additionally famous that the vulnerability is trivial to use and requires no authentication. The one prerequisite is that Tomcat makes use of file-based session storage.
“Whereas this exploit abuses session storage, the larger difficulty is partial PUT dealing with in Tomcat, which permits importing virtually any file wherever,” it added. “Attackers will quickly begin shifting their ways, importing malicious JSP recordsdata, modifying configurations, and planting backdoors outdoors session storage.”
Customers working affected variations of Tomcat are suggested to replace their cases as quickly as doable to mitigate potential threats.