Overview
The recently discovered vulnerability CVE-2025-55157 has raised concerns in the cybersecurity community due to its potential to compromise systems or lead to data leakage. The vulnerability lies within Vim, the widely used open-source command line text editor. Users who are running Vim versions between 9.1.1231 and 9.1.1400 are at risk of this vulnerability, which can lead to memory corruption during the processing of nested tuples in Vim script. The severity of this threat is highlighted by its high CVSS Score, making it an issue that demands immediate attention.
Vulnerability Summary
CVE ID: CVE-2025-55157
Severity: High – 8.8 CVSS Score
Attack Vector: Direct user interaction via script execution
Privileges Required: User-level privileges
User Interaction: Required
Impact: Memory corruption potentially leading to system compromise or data leakage
Affected Products
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Product | Affected Versions
Vim | 9.1.1231 to 9.1.1400
How the Exploit Works
The vulnerability CVE-2025-55157 is triggered when processing nested tuples in Vim script, specifically when an error occurs during the evaluation. This error can trigger a use-after-free scenario in Vim’s internal tuple reference management. This occurs when the tuple_unref() function accesses memory that has already been freed due to improper lifetime handling, which in turn leads to memory corruption.
Conceptual Example Code
Given the nature of this vulnerability, it is exploited through the execution of Vim scripts that contain nested tuples. An example of this might look like the following:
" Nested Tuples
let nested_tuple = [(1,2), (3,4)]
" Triggering error during evaluation
execute 'let (' . nested_tuple[0] . ',) = [1]'This pseudocode demonstrates a conceptual scenario where the vulnerability might be exploited. It creates a nested tuple and then triggers an error during evaluation, which could potentially lead to memory corruption.
Mitigation Guidance
Users are urged to apply the vendor patch as soon as possible, as this is the most secure solution. The vulnerability has been patched in Vim version 9.1.1400, so updating to this or a later version will resolve the issue. In the meantime, or if an immediate update is not possible, it is recommended to use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation measure. These systems can detect and block attempts to exploit the vulnerability.