Use-after-free via curl_easy_pause() in CURLMOPT_SOCKETFUNCTION callback

Summary

Calling `curl_easy_pause()` within the event-based `CURLMOPT_SOCKETFUNCTION` callback triggers a use-after-free vulnerability, where libcurl attempts to store a flag using a dangling struct pointer immediately after that pointer's memory has been freed. A flaw was found in libcurl. When `curl_easy_pause()` is called within the event-based `CURLMOPT_SOCKETFUNCTION` callback, a use-after-free vulnerability is triggered. This occurs because libcurl attempts to store a flag using a pointer to memory that has already been freed. An attacker could potentially exploit this to cause a denial of service or execute arbitrary code. This Important flaw in libcurl stems from a use-after-free vulnerability when `curl_easy_pause()` is called within the `CURLMOPT_SOCKETFUNCTION` callback. This could allow an attacker to achieve denial of service or arbitrary code execution without requiring user interaction or elevated privileges. While dependent on a specific application implementation, the broad adoption of libcurl means Red Hat products leveraging this callback pattern could be affected. Red Hat severity: Important — CVSS 7.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L). Weakness: CWE-825. No fixing RHSA erratum has published yet; monitor the Red Hat CVE page and patch when it ships.