CVE-2023-36478: High Vulnerability in Eclipse Jetty

CVE-2023-36478 is a high-severity vulnerability found in Eclipse Jetty, specifically affecting versions 11.0.0 through 11.0.15, 10.0.0 through 10.0.15, and 9.0.0 through 9.4.52. This vulnerability allows an integer overflow in `MetaDataBuilder.checkSize`, which can lead to HTTP/2 HPACK header values exceeding their size limit. The flaw arises when the length is extremely large and huffman encoding is enabled, causing a multiplication error that results in a negative length, thus bypassing critical checks. As a result, attackers may exploit this vulnerability to allocate excessive buffers on the server, potentially leading to a denial of service (DoS) condition.

The vulnerability has been assigned a CVSS score of 7.5, indicating high severity. Organizations utilizing affected versions of Eclipse Jetty should be aware of the potential risk this issue poses, especially in environments reliant on HTTP/2. The vulnerability was published on October 10, 2023, and has been classified under CWE-190 (Integer Overflow or Wraparound) and CWE-400 (Uncontrolled Resource Consumption).

Organizations should prioritize patching immediately. Fixed versions are available, specifically 11.0.16, 10.0.16, and 9.4.53. As there are no known workarounds, updating to these versions is essential to mitigate the risk of exploitation.

It is important to note that this vulnerability affects not only Eclipse Jetty but also related components in environments where Jenkins and Debian Linux are utilized. Users should ensure that all components interfacing with Jetty are also updated to the recommended versions.

Vulnerability Details

Eclipse Jetty provides a web server and servlet container. In versions 11.0.0 through 11.0.15, 10.0.0 through 10.0.15, and 9.0.0 through 9.4.52, an integer overflow in `MetaDataBuilder.checkSize` allows for HTTP/2 HPACK header values to exceed their size limit. `MetaDataBuilder.java` determines if a header name or value exceeds the size limit, and throws an exception if the limit is exceeded. However, when length is very large and huffman is true, the multiplication by 4 in line 295 will overflow, and length will become negative. `(_size+length)` will now be negative, and the check on line 296 will not be triggered. Furthermore, `MetaDataBuilder.checkSize` allows for user-entered HPACK header value sizes to be negative, potentially leading to a very large buffer allocation later on when the user-entered size is multiplied by 2. This means that if a user provides a negative length value (or, more precisely, a length value which, when multiplied by the 4/3 fudge factor, is negative), and this length value is a very large positive number when multiplied by 2, then the user can cause a very large buffer to be allocated on the server. Users of HTTP/2 can be impacted by a remote denial of service attack. The issue has been fixed in versions 11.0.16, 10.0.16, and 9.4.53. There are no known workarounds.

Technical Analysis

The root cause of CVE-2023-36478 lies in the `MetaDataBuilder.checkSize` method of Eclipse Jetty, where integer overflow occurs. The attack vector is network-based, as an attacker can exploit this vulnerability over HTTP/2 by sending crafted headers. The attack complexity is low, requiring no privileges and no user interaction. If successfully exploited, the availability impact is high, as a large buffer allocation may result in service disruption.

The confidentiality and integrity impacts are minimal, as the vulnerability does not allow unauthorized access to sensitive data or alteration of existing data. However, organizations must remain vigilant, as the potential for a denial of service could lead to significant downtime.

Risk & Impact Analysis

Risk to organizations includes potential denial of service attacks that could disrupt operations and lead to financial losses. The blast radius for this vulnerability is significant, especially for organizations relying on Jetty for web services. Immediate action is required to mitigate risks associated with this vulnerability. The CVSS score of 7.5 indicates a high urgency for remediation, and organizations should prioritize patching as part of their vulnerability management program.

With the growing reliance on web applications, the impact of such vulnerabilities can cascade through services, affecting availability and potentially leading to a wider security incident. Therefore, timely patching is essential for maintaining operational integrity.

Exploitation Status

Affected Versions

The affected versions of Eclipse Jetty are 11.0.0 through 11.0.15, 10.0.0 through 10.0.15, and 9.0.0 through 9.4.52. Organizations should upgrade to versions 11.0.16, 10.0.16, and 9.4.53 to mitigate the vulnerability.

Mitigation & Remediation

To mitigate this vulnerability, organizations must apply the latest patches to Eclipse Jetty. The recommended versions are 11.0.16, 10.0.16, and 9.4.53. In the absence of a patch, organizations should consider implementing configuration hardening to limit exposure. Regular security assessments are also essential to identify vulnerabilities and ensure that security measures are effective.

Organizations should validate remediation through penetration testing to identify similar weaknesses.

Detection Guidance

To detect potential exploitation of this vulnerability, organizations should monitor HTTP/2 traffic for abnormal header sizes or patterns that indicate manipulation. Log indicators that reveal unusually large buffer allocations should also be investigated. Additionally, behavioral anomalies in application performance can serve as early warning signs of an attempted exploitation.

AppSecure Threat Intelligence Insight

The long-term significance of CVE-2023-36478 emphasizes the importance of secure coding practices within web server frameworks. Integer overflow vulnerabilities can lead to severe denial of service conditions, impacting the availability of critical services. Organizations should analyze this incident to strengthen their defensive posture, ensuring robust security measures are in place to mitigate similar vulnerabilities in the future.

For further reading on vulnerability management best practices, organizations can refer to the vulnerability management program and the importance of regular security assessments.

Overall, CVE-2023-36478 serves as a critical reminder for organizations to prioritize the security of their applications and continuously assess their infrastructure against emerging threats.