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Fencer Vulns
critical 9.3

CVE-2026-55450 json

Langflow: Unauthenticated file upload leads to DoS (space exhaustion) and information leak

published 2026-06-17 4 mo ago modified 2026-10-25 14 d ago also GHSA-x223-p2gf-v735 , PYSEC-2026-224 , EUVD-2026-38511

cvss
9.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known, plus a Nuclei check

Summary

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, unauthenticated users can upload any amount of data to the server without any limitations. No need for any prior knowledge, only network access to Langflow. This can lead to space exhaustion on the server. In addition, in the response, the absolute path of the uploaded file is reported to the attacker, which is an information leak that can assist in chaining other primitives. This vulnerability is fixed in 1.9.1.

Patch / fix

  • pypi langflow 1.9.1
  • langflow langflow 1.9.1

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

1.19% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Langflow < 1.9.1 - Unauthenticated File Upload nuclei detection template
  • github.com https://github.com/langflow-ai/langflow/security/advisories/GHSA-x223-p2gf-v735 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:H
OSV 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:H
GitHub 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi langflow
<1.9.1
1.9.1

Affected products

  • langflow-ai langflow

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-306 Missing Authentication for Critical Functionality
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.