Critical Vulnerability in Emacs: Arbitrary Code Execution in Flymake Mode
Summary
RLSA-2026:85245: Important: emacs security update. Affects emacs versions < 1:27.2-18.el9_8.3. Fixed in 1:27.2-18.el9_8.3. How to fix ↓
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Background
GNU Emacs is a powerful and customizable text editor widely used for programming and text manipulation. It features a built-in scripting language (elisp) and offers advanced code editing capabilities. However, a recent security vulnerability has been identified in Flymake mode, which can lead to arbitrary code execution, posing significant risks to users.
Vulnerability Detail
The vulnerability, identified as CVE-2026-96442, allows an attacker to execute arbitrary code within the Emacs environment when Flymake mode is enabled. This can occur due to improper handling of certain inputs, leading to potential exploitation. The ramifications of this vulnerability are severe, as it could allow unauthorized access to sensitive data or system control, making it critical for users to address this issue promptly.
How To Fix
Minimum fixed version
1:27.2-18.el9_8.3
This is the first release that contains the fix.
sudo dnf update emacsTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can disable Flymake mode in Emacs to mitigate the risk of exploitation until the package is updated. This can be done by adding the following line to your Emacs configuration file: '(setq flymake-mode nil)'.
Conclusion
The identified vulnerability in Emacs poses a significant threat due to the potential for arbitrary code execution in Flymake mode. Users are strongly advised to update their Emacs installation to the latest patched version to mitigate risks. Temporary workarounds are available, but updating is the most effective solution.
See every vulnerability recorded for emacs →
FAQ
The vulnerability allows for arbitrary code execution in Flymake mode, which can be exploited by attackers.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
As a temporary measure, you can disable Flymake mode to reduce the risk of exploitation until you can apply the update.
The CVSS score for this vulnerability is 7.8, indicating a high level of severity.
The Rocky Enterprise Software Foundation and Red Hat have acknowledged and provided the security update for this vulnerability.
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