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Kestra AuthenticationFilter Authentication Bypass Leading to Unauthenticated RCE

IdentifiersCVE-2026-49869CWE-288

CVE-2026-49869 is a critical authentication bypass vulnerability in Kestra OSS affecting versions prior to 1.0.45 and 1.3.21. The flaw is in AuthenticationFilter, which exempts the public configuration endpoint from Basic Authentication by using a suffix-based path check, request.getPath().endsWith("/configs"), instead of validating the exact intended endpoint. As a result, any API path whose final segment is "configs" is incorrectly treated as public and can be accessed without authentication. An unauthenticated remote attacker can abuse this logic flaw to bypass authentication, create arbitrary workflows, and execute them. Because Kestra ships with script execution plugins such as plugin-script-shell and plugin-script-python enabled by default, exploitation can directly lead to unauthenticated remote code execution as root inside the Kestra worker container.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a remote unauthenticated attacker to fully bypass Basic Authentication for affected API paths ending in "configs". This enables unauthorized creation and execution of workflows. In default Kestra deployments, where script execution plugins are enabled, the attacker can achieve remote code execution as root within the Kestra worker container. The resulting impact includes complete compromise of confidentiality, integrity, and availability within the affected Kestra execution environment, and potentially further pivoting depending on container privileges, mounted secrets, network reachability, and surrounding infrastructure.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict network access to the Kestra API so it is not reachable by untrusted users or the public Internet. Place the service behind a reverse proxy, VPN, IP allowlist, or other access-control layer that enforces authentication before requests reach Kestra. As a defense-in-depth measure, disable or remove script execution plugins such as plugin-script-shell and plugin-script-python where not required, since these default capabilities turn the authentication bypass into direct RCE. Monitor for unauthenticated workflow creation or execution and for suspicious requests to API paths ending in "configs".

Remediation

Patch, then assume compromise.

Upgrade Kestra OSS to a fixed release: 1.0.45 or later in the 1.0.x line, or 1.3.21 or later in the 1.3.x line. The fix corrects the authentication logic so that the public configuration endpoint is not whitelisted via an unsafe suffix match. Apply the vendor-provided patched version across all exposed Kestra instances and verify that unauthenticated requests to unintended paths ending in "configs" are no longer accepted.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

6 SOURCESView more in app
What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity5

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-49869
NVD
nvd.nist.gov/vuln/detail/CVE-2026-49869
MITRE CWE · CWE-288
cwe.mitre.org