CVE-2025-49179: 
TigerVNC vulnerability analysis and mitigation

CVE-2025-49179 is a vulnerability discovered in the X Record extension of the X.Org X Server. The flaw was disclosed on June 17, 2025, and affects the RecordSanityCheckRegisterClients function which fails to properly check for integer overflow when computing request length, which allows a client to bypass length checks (NVD, Ubuntu Security).

The vulnerability is classified as an Integer Overflow (CWE-190) in the X Record extension. The RecordSanityCheckRegisterClients function lacks proper validation for integer overflow when calculating request lengths, which allows a client to bypass length checks. The issue has been assigned a CVSS v3.1 Base Score of 7.3 (High) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H (Wiz Analysis).

The vulnerability enables attackers to bypass length checks in the X Record extension, potentially leading to memory corruption. This could result in denial of service conditions, information disclosure, or possible arbitrary code execution in the X Server (Wiz Analysis).

The vulnerability requires local access with low attack complexity. No public exploits have been reported at the time of disclosure (Wiz Analysis).

Multiple vendors have released patches to address this vulnerability. Ubuntu has released fixed versions for affected releases: Ubuntu 25.04 (xorg-server 2:21.1.16-1ubuntu1.1), 24.10 (2:21.1.13-2ubuntu1.4), 24.04 LTS (2:21.1.12-1ubuntu1.4), and 22.04 LTS (2:21.1.4-2ubuntu1.7~22.04.15). Red Hat has also addressed the issue in RHEL 8, 9, and 10 through various security advisories (Ubuntu Security, Red Hat Security).