Langflow: DoS Through Lack of File Size Restriction via Deprecated Unauthenticated File Upload API

Description

A security flaw has been discovered in langflow-ai langflow up to 1.1.0. This issue affects the function create_upload_file of the file src/backend/base/Langflow/api/v1/endpoints.py of the component API Endpoint. The manipulation results in unrestricted upload. It is possible to launch the attack remotely. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Source code
Not specified
Published (advisory)
2026-04-20 03:34:42 UTC
Updated
2026-04-24 20:13:27 UTC
GitHub reviewed
2026-04-24 20:13:26 UTC
NVD published
2026-04-20 03:16:16 UTC

EPSS Score

Score Percentile
0.05% 15.39%

CVSS Scores

Base score Version Severity Vector
7.3 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
5.5 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:L)
Limited confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:L)
Limited integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:L)
Limited availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:P)
Proof-of-concept: public PoC exists; no reported exploitation and no known simplification tools.

Identifiers

CWEs

CWE id Name
CWE-284 Improper Access Control

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
pip langflow-base < 1.9.1 1.9.1

References

cvelogic Threat Intelligence