Inefficient Regular Expression Complexity in CodeMirror Markdown Mode Vulnerability
Summary
CVE-2025-6493: A vulnerability was found in CodeMirror up to 5.17.0 and classified as problematic. Affects codemirror-js versions 5.59.2+~cs0.23.109-1 – 5.65.0+~cs5.83.9-3. No fix is published. How to fix ↓
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Background
CodeMirror is a versatile text editor implemented in JavaScript for the browser. It is widely used for editing code and supports various programming languages and markup formats. The Markdown Mode of CodeMirror allows users to write and edit Markdown text efficiently. However, versions up to 5.17.0 have been found to contain a vulnerability that can lead to performance issues due to inefficient regular expression handling.
Vulnerability Detail
A vulnerability identified as CVE-2025-6493 affects the Markdown Mode of CodeMirror up to version 5.17.0. This issue arises from inefficient regular expression complexity, which can be exploited remotely. Attackers may leverage this vulnerability to degrade application performance, potentially leading to denial of service. The exploit has been publicly disclosed, and while not all code samples are available, the risk remains significant for applications using the affected versions.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users may limit the input size or sanitize the input to avoid triggering the inefficient regular expressions. This can be done by implementing input validation checks in the application code.
Conclusion
CVE-2025-6493 represents a significant vulnerability in CodeMirror's Markdown Mode, affecting versions up to 5.17.0. Users are strongly encouraged to update to a patched version to avoid potential performance issues. Temporary workarounds can help mitigate risks until an update can be applied.
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FAQ
CVE-2025-6493 is a vulnerability in CodeMirror's Markdown Mode that leads to inefficient regular expression complexity, potentially allowing remote attackers to degrade application performance.
The vulnerability affects CodeMirror versions up to 5.17.0. Users are advised to upgrade to a version higher than 5.17.0.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The CVSS score for this vulnerability is 5.3, indicating a moderate level of risk.
If immediate updates are not possible, consider implementing input validation and limiting input size as a temporary workaround to mitigate the risk.
References
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