Unpatched Langflow Path Traversal Flaw Exploited for Unauthenticated RCE
Attackers are actively exploiting CVE-2026-5027, a high-severity path traversal vulnerability in the open-source AI application platform Langflow, to write files to arbitrary locations on target systems and potentially achieve remote code execution. The flaw affects the POST /api/v2/files endpoint, where the filename parameter is not properly sanitized, and exploitation is made more severe by Langflow's default unauthenticated auto-login behavior, which lets attackers obtain a valid session token with a single unauthenticated request. VulnCheck reported observed attacks writing apparent test files to victim hosts, while Tenable identified the issue and assigned it a CVSS 8.8 score.
Internet exposure increases the risk: Censys data indicates about 7,000 Langflow instances are reachable online, with the largest concentration in North America. The exploitation report also fits a broader pattern of sustained attacker interest in Langflow, with other vulnerabilities including CVE-2026-0770, CVE-2026-21445, CVE-2026-33017, and CVE-2025-34291 also reported as exploited in 2026; the last has been linked in public reporting to the Iranian state-backed group MuddyWater. Separately, a newly disclosed flaw in Roxy-WI (CVE-2026-45556) shows a similar arbitrary file-write-to-RCE pattern on managed load balancers, but no public patch was available at publication.
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How this story unfolded
3 events from the most recent confirmed update back to the earliest known activity.
VulnCheck reports first observed exploitation of Langflow CVE-2026-5027
VulnCheck reported in-the-wild exploitation of CVE-2026-5027, a high-severity path traversal flaw in Langflow that can enable arbitrary file write and potential remote code execution. The observed activity involved attackers writing apparent test files to victim systems, aided by Langflow's default unauthenticated auto-login behavior.
CVE-2026-45556 in Roxy-WI is publicly disclosed without a patch
A public disclosure described CVE-2026-45556 in Roxy-WI versions 8.2.6.4 and earlier as an authenticated path traversal and arbitrary file write issue in the WAF rule save functionality. The write primitive could be used to place files such as cron jobs on managed load balancers, leading to downstream remote code execution, and no public patch was available at publication.
Tenable publicly discloses Langflow CVE-2026-5027
Tenable publicly disclosed CVE-2026-5027 on March 27, 2026, describing a path traversal flaw in Langflow's file upload endpoint that could allow arbitrary file writes. The report said the issue had been reported earlier without response, and later fixes were released in langflow-base 0.8.3 and Langflow 1.9.0.
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Sources
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Langflow Critical Arbitrary File Write Path Traversal Vuln 2026-5027
linuxsecurity.com
Open sourceUnpatched Langflow Flaw CVE-2026-5027 Exploited for Unauthenticated RCE
thehackernews.com
Open sourceCVE-2026-45556 - Roxy-WI: Authenticated arbitrary file write on every managed load balancer (and downstream RCE) via WAF rule save `config_file_name`
cvefeed.io
Open sourcePath traversal flaw in AI dev platform Langflow exploited in attacks
bleepingcomputer.com
Open sourceDirectory Traversal in langflow-base | CVE-2026-5027 | Snyk
security.snyk.io
Open source#kevs | Caitlin Condon
linkedin.com
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Actively Exploited Langflow RCE Exposed AI Pipeline Secrets and Triggered CISA KEV Listing
Threat actors rapidly exploited **CVE-2026-33017**, a critical unauthenticated remote code execution flaw in Langflow’s public flow build endpoint, allowing arbitrary Python code to reach an unsandboxed `exec()` path with a single crafted request. The bug affects Langflow versions prior to **1.9.0** and stems from the `POST /api/v1/build_public_tmp/{flow_id}/flow` endpoint accepting attacker-controlled flow data through an optional parameter. Researchers and vendor advisories said the issue is distinct from **CVE-2025-3248** because the vulnerable endpoint is intentionally public, meaning the fix required removing attacker-supplied flow data from that execution path rather than simply adding authentication. Sysdig and other researchers reported exploitation beginning within about **20 hours** of disclosure, with attackers scanning for exposed instances, validating code execution, reading files such as `.env`, `.db`, and `/etc/passwd`, stealing credentials, API keys, and database secrets, and attempting follow-on payload delivery from infrastructure including `173.212.205[.]251:8443`. The severity prompted **CISA** to add the flaw to its **Known Exploited Vulnerabilities** catalog and order federal agencies to remediate by **April 8, 2026** or discontinue use if they could not secure affected systems. Security guidance across the reports urged organizations to upgrade to **Langflow 1.9.0 or later**, restrict or remove internet exposure of the vulnerable endpoint, monitor outbound connections, and rotate secrets if compromise is suspected.
Jun 8, 2026
Critical Root Access and Arbitrary File Write Flaws Disclosed in Network-Exposed Systems
Two high-severity vulnerabilities were disclosed affecting exposed application and device management surfaces, including a flaw that can give attackers **root access** and another that enables **arbitrary file write** through path traversal. **CVE-2026-3587** describes an unauthenticated remote attack path in a hidden CLI function that lets an attacker escape a restricted prompt and gain root access to the underlying Linux operating system, potentially leading to full device compromise. The issue was mapped to `CWE-912` and assigned a `CVSS v3.1` score vector of `AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`, with CERT VDE publishing advisory `VDE-2026-020`. A separate vulnerability, **CVE-2026-5027**, affects Langflow's `POST /api/v2/files` endpoint, where improper sanitization of the multipart `filename` parameter allows path traversal using `../` sequences. An authenticated attacker can exploit the bug to write files to arbitrary filesystem locations, creating a route to compromise confidentiality, integrity, and availability. The flaw was classified as `CWE-22`, carries the `CVSS v3.1` vector `AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`, and is referenced in Tenable advisory `TRA-2026-26`.
Mar 27, 2026
Langflow Flaws Enable Cross-Tenant Access and Fuel Cryptominer Intrusions
Multiple vulnerabilities in **Langflow** have exposed AI application deployments to both account-to-account abuse and active compromise. **`CVE-2026-33760`** affects versions before **1.9.0** and allows authenticated users to read, modify, rename, or delete other users’ messages, sessions, build artifacts, and LLM transaction logs through seven `/api/v1/monitor` endpoints that fail to enforce ownership checks. A separate flaw, **`CVE-2026-55255`**, affects versions before **1.9.2** and lets an authenticated attacker execute another user’s flow through the `/api/v1/responses` endpoint by supplying a victim `flow_id`, giving the issue a critical **CVSS 9.9** rating. At the same time, defenders are tracking a cryptocurrency-mining campaign exploiting **`CVE-2026-33017`**, an unauthenticated remote code execution bug in Langflow, to compromise exposed instances and deploy Monero miners. Threat research says the malware disables security controls, installs persistence, and can enable lateral movement through reused SSH keys; observed infrastructure includes **`83.142.209.214`** and **`94.156.64.241`**. Organizations running Langflow are being urged to upgrade to **1.9.0** and **1.9.2** or later as applicable, verify access-control enforcement, restrict public exposure of Langflow services, and treat signs of miner activity or unauthorized flow execution as a significant incident.
Jun 24, 2026