CVE-2023-3255 : What You Need to Know

This CVE, assigned by Red Hat, pertains to a vulnerability found in the QEMU built-in VNC server. The flaw could potentially lead to an infinite loop in the inflate_buffer() function, resulting in a denial of service when processing certain ClientCutText messages.

Understanding CVE-2023-3255

The vulnerability identified as CVE-2023-3255 revolves around an issue within the VNC server of QEMU, posing a risk of a denial of service attack due to an infinite loop occurrence.

What is CVE-2023-3255?

The flaw found in the QEMU built-in VNC server involves processing ClientCutText messages incorrectly, leading to an infinite loop when handling an attacker controlled zlib buffer. This flaw can be exploited by a remote authenticated client capable of sending a clipboard to the VNC server, thereby triggering a denial of service.

The Impact of CVE-2023-3255

If exploited, CVE-2023-3255 could allow a remote authenticated attacker to cause a denial of service by triggering an infinite loop in the inflate_buffer() function of the QEMU VNC server. This has the potential to disrupt the normal operations of the server, affecting its availability.

Technical Details of CVE-2023-3255

The vulnerability carries a CVSSv3.1 base score of 6.5, categorizing it as having a moderate severity level. The attack complexity is rated as low, with a network-based attack vector and high availability impact.

Vulnerability Description

The flaw arises from an incorrect exit condition within the inflate_buffer() function of the QEMU built-in VNC server while handling ClientCutText messages, potentially leading to an infinite loop.

Affected Systems and Versions

Red Hat Enterprise Linux 8 (virt:rhel/qemu-kvm) and Red Hat Enterprise Linux 9 (qemu-kvm) are affected.
Versions such as Red Hat Enterprise Linux 6 (qemu-kvm), 7 (qemu-kvm, qemu-kvm-ma), and Extra Packages for Enterprise Linux are unaffected by this vulnerability.

Exploitation Mechanism

Remote authenticated clients capable of sending a clipboard to the VNC server can exploit this vulnerability, initiating a denial of service attack through an infinite loop in the inflate_buffer() function.

Mitigation and Prevention

It is crucial to take immediate steps to mitigate the risks posed by CVE-2023-3255 and establish long-term security practices to prevent future vulnerabilities.

Immediate Steps to Take

Red Hat recommends applying the necessary security updates as soon as patches are available to address the vulnerability.
Organizations should monitor for any unusual network activity that could indicate exploitation attempts related to this CVE.

Long-Term Security Practices

Implementing network segmentation, access controls, and regular security audits can help bolster overall cybersecurity posture and reduce the likelihood of successful attacks targeting vulnerabilities like CVE-2023-3255.

Patching and Updates

Ensure that all relevant systems, particularly affected Red Hat Enterprise Linux versions, are promptly patched with the provided security updates to mitigate the risks associated with CVE-2023-3255.