CVE-2026-27598

The CreateNewDAG API endpoint (POST /api/v1/dags) does not validate the DAG name before passing it to the file store. While RenameDAG calls core.ValidateDAGName() to reject names containing path separators (line 273 in dags.go), CreateNewDAG skips this validation entirely and passes user input directly to dagStore.Create().

In internal/persis/filedag/store.go, the generateFilePath function (line 493) checks if the name contains a path separator, and if so, resolves it via filepath.Abs(name), completely ignoring the baseDir. This means a name like ../../tmp/pwned will write a file to /tmp/pwned.yaml instead of the DAGs directory.

Affected code:

internal/service/frontend/api/v1/dags.go line 120-170, CreateNewDAG handler, no call to ValidateDAGName

internal/persis/filedag/store.go line 493-498, generateFilePath resolves absolute path when name contains separator

internal/persis/filedag/store.go line 213, Create calls generateFilePath and writes attacker-controlled YAML content to the resolved path

PoC:

curl -X POST http://localhost:8080/api/v1/dags \
  -H "Content-Type: application/json" \
  -d '{
    "name": "../../tmp/path-traversal-proof",
    "spec": "steps:\n  - command: id > /tmp/pwned\n"
  }'

After this request, a file /tmp/path-traversal-proof.yaml will be created with the attacker-supplied content. The file will be written with the permissions of the dagu process.

An authenticated user with DAG write permissions can write arbitrary YAML files anywhere on the filesystem (limited by the process permissions). Since dagu executes DAG files as shell commands, writing a malicious DAG to the DAGs directory of another instance or overwriting config files can lead to remote code execution.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

Kodem intelligence

1. What is CVE-2026-27598? CVE-2026-27598 is a high-severity path traversal vulnerability in github.com/dagu-org/dagu (go), affecting versions <= 1.16.7. No fixed version is listed yet. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. Which versions of github.com/dagu-org/dagu are affected by CVE-2026-27598? github.com/dagu-org/dagu (go) versions <= 1.16.7 is affected.
3. Is there a fix for CVE-2026-27598? No fixed version is listed for CVE-2026-27598 yet. Monitor the advisory for updates and apply mitigations in the interim.
4. Is CVE-2026-27598 exploitable, and should I be worried? Whether CVE-2026-27598 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-27598 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-27598? No fixed version is listed yet. In the interim: Resolve the canonical path after applying any user-supplied input, and verify it remains within the intended directory before accessing it.