CVE-2025-22134 in vim
Summary
by MITRE • 01/13/2025
When switching to other buffers using the :all command and visual mode still being active, this may cause a heap-buffer overflow, because Vim does not properly end visual mode and therefore may try to access beyond the end of a line in a buffer. In Patch 9.1.1003 Vim will correctly reset the visual mode before opening other windows and buffers and therefore fix this bug. In addition it does verify that it won't try to access a position if the position is greater than the corresponding buffer line. Impact is medium since the user must have switched on visual mode when executing the :all ex command. The Vim project would like to thank github user gandalf4a for reporting this issue. The issue has been fixed as of Vim patch v9.1.1003
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Analysis
by VulDB Data Team • 08/14/2025
The vulnerability described in CVE-2025-22134 represents a heap-buffer overflow condition within the Vim text editor that emerges during specific user interaction patterns involving buffer switching and visual mode activation. This flaw manifests when users execute the :all command while visual mode remains active, creating a scenario where Vim fails to properly terminate the visual mode state before transitioning to different buffers. The underlying technical issue stems from inadequate state management within Vim's buffer handling mechanisms, specifically in how the editor processes visual mode termination when switching between multiple buffers through the :all command. The vulnerability falls under CWE-121, heap-based buffer overflow, as it involves improper memory access patterns that can lead to memory corruption and potential exploitation.
The operational impact of this vulnerability is classified as medium severity, requiring specific user conditions to be exploited successfully. An attacker or malicious user would need to first activate visual mode within a Vim session and then execute the :all command to trigger the overflow condition. This limitation reduces the attack surface significantly compared to vulnerabilities that can be triggered automatically. The heap-buffer overflow occurs because Vim attempts to access memory locations beyond the bounds of allocated buffer space when processing visual mode data during buffer transitions. The vulnerability specifically affects scenarios where Vim tries to access positions in buffer lines that exceed the actual line length, creating a situation where memory access violations can occur. This behavior aligns with ATT&CK technique T1059.001, command and scripting interpreter, as it involves manipulation of the editor's internal state through command execution patterns that can lead to memory corruption.
The fix implemented in Vim patch version 9.1.1003 addresses this vulnerability through two primary mechanisms that enhance memory safety and state management. First, the patch ensures proper reset of visual mode before opening other windows and buffers, preventing the accumulation of invalid state information during buffer transitions. Second, the patch implements validation checks that verify buffer position access before attempting to read or write data at specific memory locations. These defensive programming measures directly address the root cause by ensuring that visual mode is properly terminated and by adding bounds checking to prevent access beyond line boundaries. The patch demonstrates effective remediation through proper resource management and input validation, preventing the heap corruption that could potentially lead to arbitrary code execution or denial of service conditions. The fix represents a comprehensive approach to memory safety that aligns with secure coding practices and industry standards for preventing buffer overflow vulnerabilities in text editors and similar applications.