A critical security vulnerability identified as CVE-2026-81838 has been uncovered within awsdac, a popular diagram-as-code command-line interface tool utilized for generating Amazon Web Services architecture diagrams from YAML definitions. Published on August 27, 2026, under Bulletin ID 2026-090-AWS, the advisory details an awsdac Zip Slip path traversal flaw that could potentially allow an attacker to achieve arbitrary code execution on local developer machines or continuous integration pipelines.
Understanding the awsdac Path Traversal Flaw
The security issue centers around how the CLI utility manages and processes compressed archives. Specifically, when awsdac extracts a zip archive referenced by a ZipFile resource inside a definition file, it fails to adequately sanitize file paths. Consequently, a maliciously crafted archive can exploit this vulnerability to write files completely outside of the intended cache directory, targeting any filesystem path that is writable by the user executing the tool. Depending on the exact nature and destination of the files written, this path traversal flaw can escalate rapidly to arbitrary code execution.
Security analysts note that exploiting CVE-2026-81838 requires the tool to process a definition file originating from an untrusted source. This threat vector typically manifests under specific operational conditions:
- Running awsdac without proper definition trust restrictions, a vulnerability prevalent in versions prior to 0.22.4 which featured no trust distinction. (Beginning with version 0.22.4, the tool enforces the
--allow-untrusted-definitionsflag). - Loading a definition file directly from the local filesystem utilizing
Type: LocalFile, an action that completely bypasses the built-in definition URL allowlist.
Impact and Risk Assessment for Environments
The primary risk scenario involves automated CI/CD environments that routinely process infrastructure definition files sourced from untrusted or semi-trusted external contributors. Because awsdac functions strictly as a client-side CLI utility designed to render architecture diagrams locally on a workstation or runner, AWS has clarified that the flaw does not compromise any underlying cloud service, AWS infrastructure account, or customer data. The resulting impact is strictly confined to the local host machine where the vulnerable tool is executed.
The vulnerability impacts a broad range of software iterations:
- Affected Software: awsdac
- Impacted Versions: Versions 0.10 through 0.23 inclusive
- Publication Date: August 27, 2026, at 1:00 PM PDT
- Scope: AWS Security Bulletin 2026-090-AWS
Users and administrative teams operating affected versions of the tool are strongly advised to review their CI/CD pipelines, restrict the execution of untrusted definition files, and adopt updated software versions that incorporate necessary trust boundaries and flag requirements.
Source: Original Article
