CVE-2026-96269 in Emacs
Summary
by MITRE • 09/22/2026
GNU Emacs 28.1 through 31.1 allows arbitrary code execution upon opening a file, because an untrusted value of read-symbol-shorthands affects the intern and unintern functions. This affects the default configuration; no particular user settings are required to trigger it.
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Analysis
by VulDB Data Team • 09/22/2026
The vulnerability identified in GNU Emacs versions 28.1 through 31.1 represents a critical security flaw that allows for arbitrary code execution when an untrusted file is opened by the editor. This issue stems from improper handling of read-symbol-shorthands, which are configuration settings used to define shorthand notations for symbols within Lisp expressions. When Emacs processes these shorthands during the parsing phase, it interacts with internal functions such as intern and unintern that manage symbol tables in the underlying Common Lisp environment. An attacker can craft a malicious file containing specially constructed read-symbol-shorthand definitions that exploit this interaction to inject arbitrary commands into the execution context of the editor.
From a technical perspective, the root cause lies in how Emacs evaluates these shorthand expansions without sufficient validation or sandboxing constraints. The intern function adds symbols to the global symbol table while unintern removes them, and both operations can have side effects if manipulated incorrectly through crafted input. By embedding malicious code within the structure of read-symbol-shorthands, an adversary triggers unintended evaluation paths that bypass standard security controls inherent in Emacs configuration files. This flaw is particularly severe because it affects the default configuration, meaning no specific user settings or customizations are required to exploit it. Any user opening a compromised file under normal operating conditions becomes vulnerable to remote code execution attacks.
The operational impact of this vulnerability extends beyond simple data corruption or denial-of-service scenarios. Since arbitrary code execution occurs within the context of the Emacs process, attackers can potentially access sensitive files stored on the local system, exfiltrate confidential information, install additional malware, or use the compromised machine as part of a larger botnet infrastructure. Given that many developers and technical professionals rely heavily on GNU Emacs for coding tasks involving complex scripting languages like Lisp, Python, or shell scripts, this vulnerability poses significant risks to productivity environments where trust in file sources may be assumed but not rigorously enforced.
Industry standards classify such vulnerabilities under categories related to improper input validation and insecure default configurations. Specifically, this aligns with CWE-94 Improper Control of Generation of Code (Code Injection) due to the ability to inject executable code via manipulated inputs. Additionally, it relates to CWE-201 Insertion of Sensitive Information Into Sentinel Value as well as aspects of CWE-78 OS Command Injection depending on how the executed commands interact with external systems. From a threat modeling perspective using MITRE ATT&CK frameworks, this vulnerability supports techniques associated with Initial Access through spearphishing attachments and Execution via command-line interface exploitation vectors commonly seen in advanced persistent threats targeting developer workstations.
Mitigation strategies should focus primarily on updating to patched versions of GNU Emacs where these flaws have been addressed by developers implementing stricter validation mechanisms for read-symbol-shorthands before they are processed internally. Until updates can be applied, users must exercise extreme caution when opening files from untrusted sources or those received via email and other potentially compromised channels. Disabling automatic evaluation features within configuration settings may provide temporary relief although complete protection requires version upgrades combined with enhanced awareness training regarding safe file handling practices in professional development environments prone to targeted cyberattacks exploiting editor-specific weaknesses.