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CVE-2026-7872 is a path traversal vulnerability (CWE-22) identified in IBM Langflow OSS versions 1.0.0 through 1.10.0. The flaw resides in the `_unpack_bundle` function within base_file.py, which handles the extraction of tar archives uploaded via the file component. A timing flaw in the symbolic link validation logic allows an attacker to upload a specially crafted tar archive containing embedded symlinks. The application performs lexical resolution of symbolic link members before writing them to disk, permitting validation to pass while the subsequent extraction creates symlinks that point outside the intended directory.
By controlling a file ingested into the system—for example, through a RAG chatbot—an attacker can direct the node to read any file on the filesystem by absolute path. This includes the application’s `secret_key` file, which contains the JWT token secret. The vulnerability requires network access over HTTP/HTTPS to the Langflow file upload endpoint and, while rated with no required privileges and no user interaction, Langflow’s documented default configuration of `AUTO_LOGIN` enabled makes the authentication barrier trivial to bypass in practice.
Successful exploitation grants read access to any file accessible to the application process, including JWT signing keys, database files, environment variables, and other users’ uploaded content. Extracting the JWT signing key allows forging valid authentication tokens for any user, including administrators, constituting a full authentication bypass. In Langflow’s architecture, administrative access further enables downstream remote code execution via Python Interpreter nodes.
IBM has released version 1.10.1 to remediate the flaw.
DailyCVE Form:
Platform: IBM Langflow OSS
Version: 1.0.0 – 1.10.0
Vulnerability: Path Traversal (CWE-22)
Severity: High (CVSS 7.5)
Date: 2026-07-17
Prediction: 2026-07-20 (Patched in 1.10.1)
What Undercode Say:
Analytics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Confidentiality Impact: High
- Integrity Impact: None
- Availability Impact: None
Proof of Concept (PoC):
Create a symlink pointing to Langflow's JWT secret key file ln -s /path/to/langflow/secret_key symlink_target Compress the symlink into a tar archive tar -cf archive.tar symlink_target Upload the tar archive to the affected Read File component (e.g., via the Langflow file upload endpoint) After ingestion, query the connected vector database or Chatbot to retrieve the contents of the symlinked file (the JWT secret)
Exploitation Steps:
- Craft a tar archive containing symlinks that point to sensitive files (e.g., JWT signing key,
/etc/passwd, environment variables). - Upload the malicious tar archive to any affected component: Docling, Docling Serve, Read File (FileComponent), NVIDIA Retriever Extraction, Video File, or Unstructured API.
- The `_unpack_bundle` function extracts the tar and follows the symlink, exposing the target file’s contents.
- Retrieve the JWT signing key from the system.
- Forge a valid JWT token for any user ID, including administrative accounts.
- Create a new flow with a “Python Interpreter” node, inject arbitrary Python code, and execute it to achieve Remote Code Execution.
Protection:
- Immediate: Upgrade to Langflow OSS 1.10.1 or later, available via PyPI.
- Workaround: Restrict network access to file upload endpoints at the firewall or reverse-proxy level.
- Post-Mitigation: Rotate the application’s `secret_key` if filesystem exposure is suspected.
Impact:
- Confidentiality: Unauthorized read access to any file on the server, including JWT signing keys, database credentials, and environment variables.
- Authentication Bypass: Forged JWT tokens allow attackers to impersonate any user, including administrators.
- Remote Code Execution: Administrative access enables the creation and execution of Python code via Langflow’s Python Interpreter nodes, leading to full server compromise.
- Supply Chain Risk: Active exploitation has been observed in the wild, with attackers leveraging similar Langflow vulnerabilities to deploy DDoS botnets.
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Sources:
Reported By: nvd.nist.gov
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