Used in attacks· fix by 2025-05-269.8CriticalUsed by ransomware gangs

Langflow Langflow

CVE-2025-3248

Langflow contains a missing authentication vulnerability in the /api/v1/validate/code endpoint that allows a remote, unauthenticated attacker to execute arbitrary code via crafted HTTP requests.

What this means for your business

  • It affects Langflow. It matters if your company, or a supplier that handles your data, runs it.
  • Attackers are already using it. CISA added it to its list of flaws used in real attacks on 5 May 2025.
  • Ransomware gangs are known to have used it.
  • An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
  • FIRST's prediction model gives it a 100% chance of attack attempts being seen in the next 30 days, ranking above 99% of all known flaws.

What to do

  1. 1Check whether your company or your suppliers run Langflow, and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
  3. 3Treat it as urgent. US federal agencies must fix it by 26 May 2025. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
  4. 4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.

Fastnexa security experts

Attackers are already using this flaw. Is your Langflow Langflow exposed?

Tell us where you run Langflow Langflow and a Fastnexa penetration tester will check whether this flaw, or others like it, can be used against your websites, apps and network.

The full test is free for our first 10 founding clients until 31 December 2026. See the offer

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Required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

CISA’s wording, unedited.

Scoring

CVSS
9.8 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-306
Assigned by
disclosure@vulncheck.com

Dates

Published
2025-05-05
Last modified
2026-10-08
Added to KEV
2025-05-05
Remediation due
2025-05-26
Sources
CISA KEV, NVD

Affected products

  • Langflow Langflow- 1.3.0

As listed in the NVD configuration data. Not a statement about your estate.

References