CVE-2026-7872: Langflow Auth Bypass Vulnerability

CVE-2026-7872 Overview

CVE-2026-7872 is a path traversal vulnerability [CWE-22] in IBM Langflow OSS versions 1.0.0 through 1.10.0. An authenticated attacker can read arbitrary files from the underlying host, including the JSON Web Token (JWT) signing key used by the application. Once the signing key is obtained, the attacker can forge valid authentication tokens for any user, including administrative accounts. The flaw affects Langflow deployments on Linux, macOS, and Windows hosts.

Critical Impact
Attackers with any authenticated Langflow account can extract the JWT signing secret and impersonate arbitrary users, resulting in full account takeover and unauthorized access to connected AI workflows and data sources.

Affected Products

IBM Langflow OSS 1.0.0 through 1.10.0
Deployments running on Linux, macOS, and Microsoft Windows hosts
Any Langflow instance exposed to authenticated but low-privilege users

Discovery Timeline

2026-07-17 - CVE-2026-7872 published to the National Vulnerability Database
2026-07-20 - Entry last modified in NVD

Technical Details for CVE-2026-7872

Vulnerability Analysis

CVE-2026-7872 is a path traversal weakness that permits authenticated users to escape the intended file-serving directory. The Langflow HTTP endpoints responsible for handling file references do not correctly validate user-supplied paths. Attackers submit crafted path components containing ../ sequences to reach sensitive files outside the application root.

The most damaging target is the JWT signing key stored on the server filesystem. Langflow uses this key to sign authentication tokens issued to users. Once an attacker retrieves the key, they can generate forged tokens with arbitrary subject claims. This transforms a low-privilege authenticated account into a full impersonation primitive against every user in the deployment, including administrators.

The issue is scored 8.1 and reflects network-reachable exploitation, low attack complexity, and low required privileges. Confidentiality and integrity impacts are high because file disclosure leads directly to authentication forgery.

Root Cause

The root cause is improper limitation of a pathname to a restricted directory [CWE-22]. Langflow accepts file identifiers from authenticated requests and concatenates them into filesystem paths without canonicalizing or validating that the resolved path remains within an allow-listed directory. Traversal sequences and absolute paths are honored by the file read logic.

Attack Vector

The attacker requires only valid authenticated credentials to any Langflow account. They send a crafted HTTP request to a vulnerable file-handling endpoint with a path parameter containing traversal characters. The server resolves the path outside the intended directory and returns the file contents. Attackers first retrieve the JWT signing key, then use it offline to sign new tokens claiming the identity of an administrator. Subsequent requests presenting the forged token are accepted as legitimate.

No verified public exploit code is available at this time. See the IBM Security Advisory for authoritative technical details.

Detection Methods for CVE-2026-7872

Indicators of Compromise

HTTP requests to Langflow endpoints containing ../, ..%2f, or absolute path segments in file-related parameters
Access log entries showing reads of files outside the Langflow application directory, particularly configuration files and secret material
JWT tokens presenting valid signatures but with issuance timestamps, IP addresses, or user agents inconsistent with legitimate sessions
Sudden appearance of administrative actions from accounts that historically lacked elevated privileges

Detection Strategies

Inspect reverse proxy and application logs for path traversal patterns targeting Langflow file endpoints
Correlate authentication events by user against source IP and device fingerprint to surface impossible-travel or session anomalies indicative of forged tokens
Alert on any process reading Langflow secret files outside expected service accounts or maintenance windows

Monitoring Recommendations

Enable verbose HTTP request logging on Langflow front-ends and forward logs to a centralized analytics platform
Monitor filesystem access to the JWT signing key file with host-based auditing such as auditd on Linux or equivalent controls on Windows and macOS
Track administrative API calls and privilege changes issued through Langflow for out-of-band activity

How to Mitigate CVE-2026-7872

Immediate Actions Required

Upgrade IBM Langflow OSS to a fixed release above 1.10.0 as directed in the IBM Security Advisory
Rotate the JWT signing key immediately after patching to invalidate any tokens forged prior to remediation
Force re-authentication of all Langflow users and revoke active sessions
Review audit logs for signs of file disclosure or unexpected administrative actions during the exposure window

Patch Information

IBM has published guidance and fixed versions through the vendor advisory. Consult the IBM Security Advisory for the specific fixed release and upgrade procedure. Apply the patch to every Langflow instance across Linux, macOS, and Windows hosts.

Workarounds

Restrict Langflow access to trusted networks using a reverse proxy or firewall until patching is complete
Disable or lock down self-registration so that only vetted users can obtain the authenticated privileges required for exploitation
Deploy a web application firewall rule that blocks requests containing traversal sequences such as ../ and ..%2f in Langflow parameters
Store the JWT signing key in a location with restrictive filesystem permissions and, where possible, outside any directory reachable by the application file handlers

bash

# Example auditd rule to monitor access to a Langflow secret file on Linux
auditctl -w /opt/langflow/config/jwt_signing_key -p rwa -k langflow_jwt_key