CVE-2023-26049 Overview
CVE-2023-26049 is a cookie smuggling vulnerability in Eclipse Jetty, a popular Java-based web server and servlet engine. The vulnerability stems from nonstandard cookie parsing behavior that allows attackers to smuggle cookies within other cookies or perform unintended actions by tampering with the cookie parsing mechanism. This can lead to information disclosure, including the potential exfiltration of HttpOnly session cookies.
Critical Impact
Attackers can bypass cookie-based security policies and potentially exfiltrate HttpOnly session identifiers (like JSESSIONID) by exploiting the nonstandard cookie parsing behavior.
Affected Products
- Eclipse Jetty (versions prior to 9.4.51, 10.0.14, 11.0.14, and 12.0.0.beta0)
- Debian Linux 10.0, 11.0, 12.0
- NetApp Active IQ Unified Manager (Linux and Windows)
- NetApp E-Series SANtricity OS Controller
- NetApp E-Series SANtricity Unified Manager
- NetApp E-Series SANtricity Web Services
Discovery Timeline
- 2023-04-18 - CVE-2023-26049 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-26049
Vulnerability Analysis
This vulnerability exploits a parsing inconsistency in how Eclipse Jetty handles cookie values that begin with double quotes. According to RFC 6265, cookie parsing should follow specific delimiters, but Jetty's implementation deviates from standard behavior when encountering quoted values.
When Jetty encounters a cookie VALUE that starts with a double quote ("), it continues reading the cookie string until it finds a closing quote—even if semicolons (which normally delimit separate cookies) are encountered within the quoted section. This parsing behavior creates an opportunity for cookie smuggling attacks.
For example, a malicious cookie header like DISPLAY_LANGUAGE="b; JSESSIONID=1337; c=d" would be parsed as a single cookie named DISPLAY_LANGUAGE with the value b; JSESSIONID=1337; c=d, rather than being correctly interpreted as three separate cookies.
Root Cause
The root cause lies in Jetty's cookie parsing implementation, which follows an older interpretation based on RFC 2965 that allowed quoted cookie values. This creates a mismatch with modern cookie handling expectations and enables attackers to embed arbitrary cookie data within quoted strings, bypassing security controls that rely on proper cookie separation.
Attack Vector
The attack is network-based and requires no authentication or user interaction. An attacker can craft a malicious HTTP request containing specially formatted cookie headers to exploit the parsing vulnerability.
The exploitation scenario works as follows:
- The attacker identifies an application using a vulnerable version of Jetty
- The attacker crafts a cookie header with a quoted value containing smuggled cookies
- If the application renders any part of the smuggled cookie value (e.g., DISPLAY_LANGUAGE), HttpOnly cookies like JSESSIONID embedded within the quoted string may be exposed
- This bypasses the HttpOnly protection mechanism designed to prevent client-side script access to sensitive session cookies
This attack is particularly dangerous when an intermediary (such as a reverse proxy or WAF) enforces cookie-based security policies, as the smuggled cookie can bypass those policies while still being processed by the Jetty server.
Detection Methods for CVE-2023-26049
Indicators of Compromise
- HTTP requests containing cookie headers with unusual quoted values spanning multiple apparent cookie definitions
- Cookie values containing embedded semicolons within double quotes
- Log entries showing unexpected cookie parsing results or malformed cookie warnings
- Session hijacking attempts following cookie exfiltration patterns
Detection Strategies
- Implement web application firewall (WAF) rules to detect cookie headers containing quoted values with embedded semicolons
- Monitor HTTP request logs for anomalous cookie header patterns, particularly values like "value; JSESSIONID=
- Deploy network intrusion detection signatures to identify potential cookie smuggling attempts
- Analyze application logs for unexpected cookie value rendering or exposure
Monitoring Recommendations
- Enable verbose cookie parsing logging in Jetty to identify potential exploitation attempts
- Monitor for session anomalies that could indicate successful cookie exfiltration
- Implement alerting for HTTP requests with unusually long or complex cookie headers
- Review access logs for patterns consistent with session hijacking following cookie smuggling
How to Mitigate CVE-2023-26049
Immediate Actions Required
- Upgrade Eclipse Jetty to version 9.4.51, 10.0.14, 11.0.14, or 12.0.0.beta0 or later immediately
- Review application code for any instances where cookie values are rendered in responses
- Audit session management practices and ensure sensitive cookies use proper security attributes
- Apply available operating system and third-party vendor patches for affected distributions
Patch Information
Eclipse has addressed this vulnerability in the following patched versions:
- Jetty 9.4.x: Upgrade to version 9.4.51 or later
- Jetty 10.x: Upgrade to version 10.0.14 or later
- Jetty 11.x: Upgrade to version 11.0.14 or later
- Jetty 12.x: Upgrade to version 12.0.0.beta0 or later
The fixes are available through the official Eclipse Jetty repository. Technical details of the patches can be found in Pull Request #9339 and Pull Request #9352. The official security advisory is available at GHSA-p26g-97m4-6q7c.
Additional vendor advisories:
Workarounds
- There are no known workarounds for this vulnerability; upgrading to a patched version is the only remediation
- As a defense-in-depth measure, avoid rendering cookie values in HTTP responses where possible
- Implement strict input validation on any cookie values that must be processed or displayed
- Consider deploying a WAF with rules to reject malformed cookie headers as a temporary mitigation layer
# Verify Jetty version and upgrade
# Check current Jetty version in Maven pom.xml or build.gradle
# For Maven, update dependency version:
# <dependency>
# <groupId>org.eclipse.jetty</groupId>
# <artifactId>jetty-server</artifactId>
# <version>11.0.14</version>
# </dependency>
# For Gradle:
# implementation 'org.eclipse.jetty:jetty-server:11.0.14'
# After updating, rebuild and redeploy the application
mvn clean install
# or
gradle clean build
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
