Code execution via malicious dependency build script
Published Aug 21, 2026 · Updated Aug 21, 2026
Malicious code in append-only-vec 0.1.9 allows remote attackers to execute arbitrary code when a dependent Rust project is compiled. The crate directly declares proc-macro1, causing Cargo to execute that dependency's build script, which downloads a malicious payload. Exposure requires version 0.1.9 to enter a dependency graph and be compiled; the payload then grants command-and-control operators code execution with the build process's privileges.
Summary
What happened
Malicious code in append-only-vec 0.1.9 allows remote attackers to execute arbitrary code when a dependent Rust project is compiled. The crate directly declares proc-macro1, causing Cargo to execute that dependency's build script, which downloads a malicious payload. Exposure requires version 0.1.9 to enter a dependency graph and be compiled; the payload then grants command-and-control operators code execution with the build process's privileges.
The record
- CVE
- CVE-2026-77650
- Published
- Aug 21, 2026
- Updated
- Aug 21, 2026
- Vendor
- David Roundy
- Product
- append-only-vec
- Classifications
- CWE-506, T1105, T1195.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 21, 2026CVE publishedPublication date reported by the CVE source.
- Aug 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.1.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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