CVE-2026-78367 in Red Hat
Summary
by MITRE • 08/24/2026
A flaw was found in rpmbuild. When rpmbuild processes a crafted tarball in tarball mode, a specially designed tar member name can lead to macro injection. This vulnerability allows a remote attacker to execute arbitrary code on the system by convincing a user to build a malicious tarball.
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Analysis
by VulDB Data Team • 08/24/2026
The vulnerability identified within the RPM Package Manager build tool, specifically affecting rpmbuild during its tarball processing mode, represents a significant security risk rooted in improper input validation and macro expansion logic. When rpmbuild is invoked with options that instruct it to process source or binary packages from tar archives rather than standard spec files, it parses metadata contained within the archive structure. The core technical flaw lies in how the tool handles member names found inside these crafted tarballs. Specifically, if a malicious actor constructs a tarball where one of the internal file paths or member identifiers contains specially designed characters and sequences that mimic RPM macro syntax, rpmbuild fails to adequately sanitize this input before passing it through its macro expansion engine. This lack of strict boundary checking allows an attacker to inject arbitrary macros into the build environment, effectively bypassing the intended isolation between package metadata and executable code logic.
From a technical perspective, this issue is classified under CWE-78 Improper Neutralization of Special Elements used in an OS Command, often referred to as OS Command Injection or Code Injection. The vulnerability exploits the trust rpmbuild places in the structural integrity of tarball contents during automated builds. By embedding malicious macro definitions within file names, such as using sequences that trigger shell execution commands when expanded by the RPM build system, an attacker can manipulate the build process itself. Since rpmbuild is a privileged tool often used to compile and package software with elevated permissions, successfully injecting code through this vector allows for arbitrary command execution on the host system where the vulnerable version of rpmbuild is running. This mechanism does not require direct network access to the target server but relies instead on social engineering or supply chain compromise tactics where a user or automated build pipeline is tricked into processing a malicious artifact.
The operational impact of this vulnerability is severe, particularly in environments that utilize continuous integration and deployment pipelines which automatically fetch and process external tarballs for package creation. If an attacker can distribute a crafted tarball through public repositories, compromised mirrors, or phishing campaigns targeting developers, they can achieve remote code execution without needing to exploit network services directly on the target machine. The attack vector is categorized under ATT&CK technique T1059 Command and Scripting Interpreter, as it leverages the system's own scripting capabilities via RPM macros to execute commands. Furthermore, this falls under MITRE ATT&CK tactic TA0002 Execution because it results in the direct execution of attacker-controlled code on the victim’s infrastructure. The severity is amplified by the fact that many Linux distributions and enterprise environments rely heavily on rpmbuild for maintaining software integrity, making successful exploitation a pathway to full system compromise or lateral movement within internal networks.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is to apply vendor-provided patches that update the version of rpm-build installed on systems where rpmbuild is used. Administrators should ensure that their package management repositories are configured to automatically pull security updates for build tools. In addition to patching, organizations should enforce strict input validation policies within their CI/CD pipelines by scanning incoming artifacts for suspicious patterns before they reach the build stage. Implementing least-privilege principles is also critical; rpmbuild operations should be executed under restricted user accounts with minimal permissions rather than as root or a privileged service account to limit the blast radius of any potential exploitation. Finally, security awareness training for developers and DevOps engineers regarding supply chain risks and safe handling of untrusted archives can reduce the likelihood of users being tricked into processing malicious tarballs manually.