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Path Traversal Arbitrary File Write in IBM Langflow OSS APIRequest
CVE-2026-8859 is a path traversal vulnerability in IBM Langflow OSS affecting versions 1.0.0 through 1.10.0. The flaw is in the APIRequest component when the "Save to File" feature is enabled. Langflow derives output filenames from the HTTP response Content-Disposition header and joins those filenames to a temporary directory path without sanitizing traversal sequences or otherwise validating the resulting path. An attacker who controls an external HTTP server contacted by the vulnerable workflow can return a crafted Content-Disposition filename containing traversal elements, causing Langflow to write files outside the intended temporary directory and into other filesystem locations writable by the Langflow process.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation allows arbitrary file write to unintended locations accessible by the Langflow process. This can enable unauthorized file creation or overwrite, compromise of application data or configuration, and potentially broader system impact depending on writable paths and runtime environment. In some deployments, including the official Docker image as described in the available reporting, the arbitrary file write can be escalated to remote code execution by placing attacker-controlled files in locations that are processed by Python at startup.
If you can’t patch tonight, do this now.
Until the fixed release is deployed, disable or avoid the APIRequest component's "Save to File" functionality when interacting with untrusted external HTTP sources. Restrict which outbound HTTP destinations Langflow workflows may contact, and run the Langflow process with the minimum filesystem permissions necessary so that unintended writes cannot reach sensitive application or system paths. Additional containment through filesystem isolation or container hardening can reduce impact.
Patch, then assume compromise.
Upgrade IBM Langflow OSS to version 1.10.1 or later, which remediates this vulnerability. The fix should ensure filenames derived from Content-Disposition headers are sanitized and constrained so writes cannot escape the intended directory. Validate canonicalized paths before file creation and reject traversal sequences or absolute paths.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.