A just lately disclosed security flaw impacting Apache Tomcat has come beneath lively 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 considerations a case of distant code execution or data 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 security delicate uploads that could be a sub-directory of a goal URL for public uploads
- Attacker information of the names of security delicate information being uploaded
- The security delicate information are additionally being uploaded by way of partial PUT
Profitable exploitation may allow a malicious consumer to view security delicate information or inject arbitrary content material into these information via a PUT request.
Moreover, an attacker may 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)
- Software was utilizing Tomcat’s file based mostly session persistence with the default storage location
- Software included a library which may be leveraged in a deserialization assault
In an advisory launched final week, the challenge 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 help for partial PUT requests,” the corporate mentioned.
“The exploit works in two steps: The attacker uploads a serialized Java session file by way of PUT request. The attacker triggers deserialization by referencing the malicious session ID in a GET request.”
Put in another 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 problem is partial PUT dealing with in Tomcat, which permits importing virtually any file anyplace,” it added. “Attackers will quickly begin shifting their techniques, importing malicious JSP information, modifying configurations, and planting backdoors outdoors session storage.”
Customers operating affected variations of Tomcat are suggested to replace their situations as quickly as potential to mitigate potential threats.
