CVE-2024-41957 in vim
Summary
by MITRE • 08/02/2024
Vim is an open source command line text editor. Vim < v9.1.0647 has double free in src/alloc.c:616. When closing a window, the corresponding tagstack data will be cleared and freed. However a bit later, the quickfix list belonging to that window will also be cleared and if that quickfix list points to the same tagstack data, Vim will try to free it again, resulting in a double-free/use-after-free access exception. Impact is low since the user must intentionally execute vim with several non-default flags, but it may cause a crash of Vim. The issue has been fixed as of Vim patch v9.1.0647
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Analysis
by VulDB Data Team • 03/16/2025
The vulnerability identified as CVE-2024-41957 resides within the Vim text editor software, specifically in versions prior to v9.1.0647. This issue manifests as a double free condition occurring in the memory management routines located at src/alloc.c line 616. The flaw represents a classic memory corruption vulnerability that arises from improper handling of memory deallocation sequences within the editor's internal data structures. The vulnerability is particularly concerning because it involves the manipulation of tagstack data and quickfix lists during window closure operations, creating a scenario where the same memory region may be freed twice, leading to potential system instability and crash conditions.
The technical implementation of this vulnerability stems from the improper sequence of memory cleanup operations when a Vim window is closed. During this process, the tagstack data associated with the window undergoes clearing and subsequent freeing operations. However, a later cleanup of the quickfix list belonging to the same window can inadvertently reference the same memory location that has already been freed. This creates a scenario where the memory management system attempts to free the same block of memory twice, resulting in a double-free condition that can manifest as a use-after-free access exception. The vulnerability is classified under CWE-415 as an improper cleanup of memory, specifically involving double free conditions that occur during the normal operation flow of the application.
The operational impact of this vulnerability is considered low by default due to the specific conditions required for exploitation. An attacker must intentionally execute Vim with several non-default command-line flags to trigger the problematic code path, making the vulnerability less likely to be exploited in casual usage scenarios. However, the potential consequences include application crashes and possible system instability when the double-free condition is successfully triggered. The vulnerability affects the stability of the Vim editor itself rather than providing direct access to system resources or executing arbitrary code, though the crash conditions could potentially be leveraged in specific denial-of-service scenarios. The issue has been addressed through the release of Vim patch v9.1.0647, which corrects the memory management sequence to prevent the double-free condition from occurring.
The remediation of this vulnerability aligns with standard software security practices and follows the ATT&CK framework's approach to memory corruption mitigation. The fix implemented in patch v9.1.0647 demonstrates proper memory management practices by ensuring that memory deallocation occurs only once per memory block, preventing the double-free scenario that could lead to undefined behavior. Organizations using Vim should prioritize updating to the patched version to eliminate the risk of potential crashes and maintain system stability. The vulnerability serves as an example of how seemingly minor memory management issues can have significant impacts on software reliability, particularly in widely-used applications like text editors where stability is paramount for user productivity. Security teams should monitor for this vulnerability in environments where Vim is deployed and ensure proper patch management procedures are in place to maintain system integrity.