CVE-2026-79992 in Red Hat
Summary
by MITRE • 08/25/2026
A flaw was found in Emacs TRAMP. A local attacker could exploit this vulnerability by processing maliciously crafted filenames. This occurs because TRAMP concatenates login arguments without proper sanitization, which are then passed to a local shell. Successful exploitation could lead to arbitrary code execution.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/25/2026
The vulnerability identified within the Tramp (Transparent Remote Access, Multiple Protocols) module of GNU Emacs represents a critical security flaw rooted in improper input validation and command injection mechanics. TRAMP is designed to facilitate transparent remote file editing by connecting to various hosts using different protocols such as SSH, FTP, or Telnet. The core issue arises from how the application handles login arguments when establishing these connections. Specifically, the software concatenates user-supplied login parameters without implementing adequate sanitization checks before passing them to a local shell interpreter. This architectural decision creates a direct pathway for command injection attacks, allowing an attacker who has access to the local system or can influence file paths processed by Emacs to execute arbitrary commands with the privileges of the user running the application.
From a technical perspective, this flaw is classified under CWE-78 Improper Neutralization of Special Elements used in an OS Command, commonly known as OS Command Injection. The vulnerability manifests when TRAMP constructs shell commands dynamically based on input that includes unsanitized strings from filenames or connection targets. Because these inputs are directly interpolated into the command string without escaping special characters such as semicolons, ampersands, or backticks, a malicious actor can inject additional shell commands. For instance, by crafting a filename containing specific metacharacters, an attacker can break out of the intended context and execute arbitrary system-level instructions. This lack of strict input validation violates fundamental secure coding principles regarding the handling of external data in command-line interfaces.
The operational impact of this vulnerability is severe due to its potential for remote code execution within the local environment where Emacs is running. Although the initial vector requires a local attacker or someone who can trick a user into opening a maliciously crafted file, the resulting compromise grants full control over the host system under the context of the vulnerable application. This means that sensitive data stored on the machine could be exfiltrated, malware could be installed, or the system could be used as a pivot point for further network attacks. The severity is compounded by the fact that Emacs is often used in development and administrative workflows where users frequently open files from untrusted sources, increasing the likelihood of exploitation if proper safeguards are not in place.
In terms of threat modeling, this vulnerability aligns with MITRE ATT&CK techniques related to Command and Scripting Interpreter abuse, specifically T1059 which covers various scripting languages including shell scripts. The attack vector typically involves Initial Access through social engineering or local privilege escalation followed by Execution via the injected command. Defenders should recognize that while TRAMP is a powerful tool for remote editing, its complexity introduces surface area for such injection flaws if input handling is not rigorously enforced.
To mitigate this risk, immediate action must be taken to update GNU Emacs and the Tramp module to versions where this concatenation flaw has been patched with proper sanitization logic. Administrators should enforce strict version control policies to ensure that all workstations running Emacs are updated promptly upon the release of security patches. Additionally, users should exercise caution when opening files from untrusted sources or network shares, as these are common vectors for triggering such vulnerabilities. Implementing application whitelisting and restricting shell access in environments where high-risk applications like Emacs operate can further reduce the blast radius if an exploitation attempt occurs. Regular audits of configuration settings related to remote file editing protocols should also be conducted to ensure that only necessary services remain active, thereby minimizing potential attack surfaces.