Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2026-5027

langflow Path Traversal Arbitrary File Write

Langflow-ai / langflow · 0

Watch CVE-2026-5027 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
4.8%
First observed
10 Jul 2026
Last observed
08 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-5027 is a vulnerability affecting Langflow-ai langflow. The 'POST /api/v2/files' endpoint does not sanitize the 'filename' parameter from the multipart form data, allowing an attacker to write files to...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Also confirmed by third-party sources.

Who is affected?

Langflow-ai / langflow 0.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

langflow Path Traversal Arbitrary File Write

The 'POST /api/v2/files' endpoint does not sanitize the 'filename' parameter from the multipart form data, allowing an attacker to write files to arbitrary locations on the filesystem using path traversal sequences ('../').

langflow-ai Affected
langflow
0
Published
27 Mar 2026
Exploitation Reported
10 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
Low
User interaction
None

Tags

nuclei_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

The Hacker News

Recorded 10 Jun 2026

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 10 Jul 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

GitHub

Recorded 02 Apr 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
The Hacker News First 2026-06-10 16:20 UTC
BleepingComputer 2026-06-10 22:20 UTC
The Shadowserver 2026-07-10 00:00 UTC
Previdian Sensors 2026-07-10 15:15 UTC
Google Threat Intelligence 2026-09-30 15:21 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

76

Attempts observed

42

Unique attacker IPs

19

Attacker countries

BG · BR · CA · CN · EE · FR · IE · IN · JP · LT · MD · MY · NL · PL · PT · SG · TN · US · VN

5

Sensors observed

CVE-2026-5027 exploitation attempts over the last 89 days

Daily events observed by Previdian sensors

Updated 11 Oct 2026

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15 Jul 2 Aug 20 Aug 7 Sep 11 Oct

First observed 10 Jul 2026 · Last observed 08 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
4
28
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-5027.yaml 11 Jun 2026

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

4.8%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE-22

Recent mention · Google Threat Intelligence

Written by: Robin Grunewald, Supriya Mazumdar, Kelli Vanderlee Introduction Google Threat Intelligence Group (GTIG) examines vulnerability...

Written by: Robin Grunewald, Supriya Mazumdar, Kelli Vanderlee Introduction Google Threat Intelligence Group (GTIG) examines vulnerability disclosure and exploitation statistics to evaluate the impact of artificial intelligence (AI) on the vulnerability threat landscape. We...

Read full advisory

All Mentions

Recent mention · Google Threat Intelligence

Written by: Robin Grunewald, Supriya Mazumdar, Kelli Vanderlee Introduction Google Threat Intelligence Group (GTIG) examines vulnerability...

Google Threat Intelligence · 30 Sep 2026

Written by: Robin Grunewald, Supriya Mazumdar, Kelli Vanderlee Introduction Google Threat Intelligence Group (GTIG) examines vulnerability disclosure and exploitation statistics to evaluate the impact of artificial intelligence (AI) on the vulnerability threat landscape. We found that AI is measurably changing not just the pace of vulnerability discovery and exploitation, but also the types and typical risk profiles of vulnerabilities that are being discovered. Key findings:  Vulnerability disclosures doubled: the number of vulnerabilities disclosed per month doubled, rising from 5,045...

Recent mention · BleepingComputer

Path traversal flaw in AI dev platform Langflow exploited in attacks

BleepingComputer · 10 Jun 2026

Attackers are actively exploiting CVE-2026-5027, a high-severity path traversal vulnerability in the AI development platform Langflow, to write arbitrary files on exposed servers. [...]

Recent mention · The Hacker News

Langflow Vulnerability CVE-2026-5027 Exploited for Unauthenticated RCE

The Hacker News · 10 Jun 2026

A high-severity security flaw in Langflow, an open-source low-code platform to build artificial intelligence (AI) applications, has come under active exploitation in the wild, according to findings from VulnCheck. The vulnerability in question is CVE-2026-5027 (CVSS score: 8.8), a case of path traversal that could allow an attacker to write files to arbitrary locations. "The 'POST /api/v2/

Recent mention · The Hacker News

Unpatched Langflow Flaw CVE-2026-5027 Exploited for Unauthenticated RCE

The Hacker News · 10 Jun 2026

A high-severity unpatched security flaw in Langflow, an open-source low-code platform to build artificial intelligence (AI) applications, has come under active exploitation in the wild, according to findings from VulnCheck. The vulnerability in question is CVE-2026-5027 (CVSS score: 8.8), a case of path traversal that could allow an attacker to write files to arbitrary locations. "The 'POST /

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

rmhowe425/POC-CVE-2026-5027

github · Created 2026-09-02 13:29:25 UTC · 0 stars · AI assessment 85%

Langflow <= 1.8.4 - Path Traversal to RCE via File Upload

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 15:21 UTC

    KEV confirmed by Google Threat Intelligence

    Exploitation attested by an external source

  2. 15:10 UTC

    Indicators of compromise added (43)

    Indicators of compromise recorded

  3. 15:10 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  4. 00:00 UTC

    KEV confirmed by The Shadowserver

    Exploitation attested by an external source

  5. 14:21 UTC

    Public PoC available

    Public proof-of-concept code published

  6. 04:30 UTC

    Nuclei template available

    Scanner coverage available

  7. 22:20 UTC

    KEV confirmed by BleepingComputer

    Exploitation attested by an external source

  8. 16:20 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  9. 14:54 UTC

    CVE published

    Vulnerability disclosed publicly

  10. 14:51 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-5027

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-5027",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.04758,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 76, "sensors": 5 }
}