CVE-2025-38545: 
Linux Kernel vulnerability analysis and mitigation

A heap-based buffer overflow vulnerability was discovered in curl and libcurl, identified as CVE-2023-38545. The vulnerability affects versions from 7.69.0 through 8.3.0, disclosed on October 11, 2023. The flaw specifically occurs in the SOCKS5 proxy handshake functionality when curl is configured to use SOCKS5 proxy modes (Ubuntu Security, NVD).

The vulnerability occurs during the SOCKS5 proxy handshake when curl is configured to pass hostname resolution to the SOCKS5 proxy. The maximum allowed hostname length is 255 bytes, and when exceeded, curl should switch to local name resolving and pass only the resolved address. However, due to a bug during slow SOCKS5 handshakes, the local variable controlling hostname resolution could receive an incorrect value, causing the oversized hostname to be copied to a heap-based buffer instead of the resolved address. The vulnerability has received a CVSS v3.1 Base Score of 9.8 (CRITICAL) with vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability can lead to memory corruption through heap-based buffer overflow, potentially resulting in program crashes or remote code execution. However, the practical impact is limited by the requirement for specific configurations using SOCKS5 proxy modes and the ability to control hostname length (GreyNoise Blog).

The vulnerability has been fixed in curl version 8.4.0. Various Linux distributions and software vendors have released security updates to address this vulnerability. Ubuntu has provided fixes for affected versions in their supported releases, including version 8.2.1-1ubuntu3.1 for 24.04 LTS and 23.10, version 7.88.1-8ubuntu2.3 for 23.04, and version 7.81.0-1ubuntu1.14 for 22.04 LTS (Ubuntu Security).