CVE-2026-77650 in append-only-vec
Summary
by MITRE • 08/21/2026
The append-only-vec crate 0.1.9 for Rust can trigger execution of malicious code when compiling a project that uses the crate, because it has a rogue dependency that registers with a command-and-control server to offer arbitrary code execution.
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability identified in append-only-vec version 0.1.9 represents a severe supply chain compromise within the Rust ecosystem, specifically involving malicious dependencies designed to exfiltrate data and execute remote commands. This incident highlights the critical risks associated with transitive dependencies in modern software development pipelines, where developers often rely on third-party crates without fully auditing their internal logic or network behavior. The core issue lies not in a traditional buffer overflow or logic error within the application code itself, but rather in the deliberate insertion of malicious payloads into a widely used library. When a project compiles using this specific version of append-only-vec, it inadvertently pulls in a rogue dependency that has been tampered with to perform unauthorized actions during the build process and potentially at runtime if linked improperly.
Technically, the flaw manifests as an arbitrary code execution vector triggered during compilation or initialization phases depending on how the crate is integrated into the host project. The malicious component registers communication channels with external command-and-control servers, effectively turning compromised systems into nodes within a botnet infrastructure. This behavior aligns closely with Common Weakness Enumeration (CWE) categories such as CWE-693, Protection Mechanism Failure, and more critically, CWE-1057, Expression Obfuscation, due to the likely use of obfuscated code to hide its malicious intent from static analysis tools. Furthermore, this attack pattern is consistent with MITRE ATT&CK techniques including T1195.002 Supply Chain Compromise: Compromise Software Supply Chain and T1071 Application Layer Protocol for command-and-control communications. The attacker leverages the trust inherent in package managers like Cargo to distribute malware under the guise of legitimate utility code, bypassing traditional perimeter defenses that focus on external network threats rather than internal build integrity.
The operational impact of this vulnerability is profound, affecting not only direct users but also downstream applications and services built upon them. Since Rust projects often compile statically linked binaries or include dependencies directly into final artifacts, the malicious code can persist in deployed software long after compilation. This allows attackers to maintain persistent access, steal sensitive information such as API keys, source code repositories, or user credentials stored within the environment where the build occurs. The presence of a command-and-control channel enables further exploitation steps, including downloading additional payloads, executing system commands with the privileges of the build process, and lateral movement across internal networks if the compromised machine has broader access rights. Organizations relying on automated CI/CD pipelines are particularly vulnerable because these systems often run with elevated permissions to facilitate deployment tasks, thereby granting the malicious code significant control over critical infrastructure.
Mitigation strategies must focus on immediate isolation and comprehensive auditing of dependencies. Developers should immediately remove version 0.1.9 of append-only-vec from their Cargo.lock files and update to a verified safe version or an alternative library if available. It is crucial to audit all transitive dependencies for any suspicious network calls, unusual file system modifications during build time, or obfuscated code segments using tools like cargo-audit or specialized software composition analysis platforms that can detect known malicious patterns in crate metadata and source files. Security teams should also implement strict allow-listing policies for package sources and enforce rigorous peer review processes for new dependencies added to the project. Monitoring network traffic from development environments for connections to unknown IP addresses or domains associated with command-and-control infrastructure is essential for early detection of similar supply chain attacks. Long-term resilience requires adopting zero-trust principles within build pipelines, ensuring that every component introduced into the software stack undergoes rigorous security validation before integration.