CVE-2026-2332: Eclipse Jetty HTTP Smuggling Vulnerability

CVE-2026-2332 Overview

CVE-2026-2332 is an HTTP Request Smuggling vulnerability in Eclipse Jetty's HTTP/1.1 parser. The vulnerability exists in how Jetty handles chunk extensions in chunked transfer encoding, specifically when parsing quoted strings. Jetty incorrectly terminates chunk extension parsing at \r\n characters inside quoted strings instead of treating this as a parsing error. This behavior allows attackers to exploit "funky chunks" techniques to inject smuggled HTTP requests.

Critical Impact

Attackers can exploit this vulnerability to bypass security controls, hijack user sessions, poison web caches, or perform cross-site scripting attacks by smuggling malicious HTTP requests through Jetty-based applications.

Affected Products

• Eclipse Jetty (HTTP/1.1 implementations using chunked transfer encoding)

Discovery Timeline

• April 14, 2026 - CVE-2026-2332 published to NVD
• April 14, 2026 - Last updated in NVD database

Technical Details for CVE-2026-2332

Vulnerability Analysis

This HTTP Request Smuggling vulnerability (CWE-444) stems from improper handling of chunk extensions in Jetty's HTTP/1.1 parser. When processing chunked transfer encoding, the parser incorrectly interprets newline characters within quoted string values of chunk extensions. According to HTTP specifications, a quoted string should properly escape or reject embedded \r\n sequences. However, Jetty's parser prematurely terminates parsing when it encounters these characters, even when they appear inside double quotes.

This parsing discrepancy creates a desynchronization between Jetty and downstream servers or proxies regarding where one HTTP request ends and another begins. An attacker can craft a malicious request with an unterminated quoted chunk extension, causing Jetty to misinterpret the request boundaries and process injected content as a separate, legitimate HTTP request.

Root Cause

The root cause lies in Jetty's chunk extension parser failing to properly handle quoted strings according to RFC 7230. The parser terminates at \r\n boundaries regardless of the quoting context, allowing attackers to inject arbitrary HTTP request data. When a chunk extension contains an opening double quote without a closing quote, followed by \r\n and additional HTTP request content, Jetty incorrectly treats the injected content as a new request rather than malformed input.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker sends a specially crafted HTTP POST request with chunked transfer encoding. The request includes a chunk extension with an unclosed quoted string containing embedded newline sequences. The vulnerability allows the attacker to inject a smuggled HTTP request that will be processed as a legitimate request by Jetty.

The attack leverages the "funky chunks" technique where malformed chunk extensions confuse the parser about request boundaries. The injected request can target any endpoint accessible through the vulnerable Jetty server, potentially bypassing authentication, accessing restricted resources, or poisoning caches.

Technical details on the "funky chunks" exploitation technique are available in the referenced security research.

Detection Methods for CVE-2026-2332

Indicators of Compromise

• HTTP requests containing chunk extensions with unclosed quoted strings followed by \r\n sequences
• Unusual patterns in chunked transfer encoding with embedded HTTP request headers within chunk extension values
• Log entries showing unexpected request paths like /smuggled appearing without corresponding client connections
• Cache entries that appear poisoned or contain unexpected content for legitimate URLs

Detection Strategies

• Implement deep packet inspection for HTTP traffic to detect malformed chunk extensions in chunked transfer encoding
• Monitor for requests with Transfer-Encoding: chunked headers containing suspicious patterns in chunk data
• Deploy web application firewalls (WAF) with rules to detect HTTP request smuggling patterns
• Review application logs for anomalous request patterns indicating successful smuggling attempts

Monitoring Recommendations

• Enable detailed HTTP access logging to capture full request headers and chunked encoding metadata
• Set up alerts for requests with unusually long chunk extensions or malformed quoting patterns
• Monitor for discrepancies between frontend proxy logs and backend Jetty server logs indicating desynchronization
• Track cache hit rates for anomalies that might indicate cache poisoning attacks

How to Mitigate CVE-2026-2332

Immediate Actions Required

• Review the GitHub Security Advisory for official patch information
• Identify all Eclipse Jetty deployments in your environment and assess exposure
• Prioritize patching internet-facing Jetty instances and those behind reverse proxies
• Monitor the Eclipse GitLab CVE Issue for updates

Patch Information

Organizations should consult the official GitHub Security Advisory for detailed patch information and affected version ranges. Update to a patched version of Eclipse Jetty as soon as one becomes available from the vendor.

Workarounds

• Deploy a reverse proxy or web application firewall in front of Jetty that strictly validates chunked transfer encoding and rejects malformed chunk extensions
• Disable chunked transfer encoding at the proxy layer if feasible for your application architecture
• Implement request normalization at the load balancer level to ensure consistent parsing between frontend and backend servers
• Configure strict Content-Length validation to reject requests that may be attempting smuggling attacks

# Example: Configure nginx as a reverse proxy with strict HTTP handling
# Add to nginx.conf server block to normalize requests
proxy_http_version 1.1;
proxy_set_header Connection "";
proxy_request_buffering on;