Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2026-55255

langflow

Langflow-ai / langflow · affected before 1.9.1

Watch CVE-2026-55255 Browse KEV feed
Severity
CVSS 8.4 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
0.9%
First observed
13 Jul 2026
Last observed
30 Sep 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-55255 is a vulnerability affecting Langflow-ai langflow. Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, an Insecure Direct Object Reference (IDOR) vulnerability...

Is it exploited?

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

Who is affected?

Langflow-ai / langflow affected before 1.9.1.

What should we do?

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

Overview

Langflow is a tool for building and deploying AI-powered agents and workflows

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, an Insecure Direct Object Reference (IDOR) vulnerability in /api/v1/responses endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.

This vulnerability is fixed in 1.9.1.

langflow-ai Affected
langflow
Before 1.9.1
Published
23 Jun 2026
Exploitation Reported
07 Jul 2026
Attack vector
Remote
Complexity
High
Privileges
Low
User interaction
None

Tags

cisa

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

CISA

Recorded 07 Jul 2026

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 13 Jul 2026

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

Proof of concept available

GitHub

Recorded 30 Jun 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.

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Source Added
CISA First 2026-07-07 17:00 UTC
CVE 2026-07-07 18:20 UTC
All CISA Advisories 2026-07-07 19:20 UTC
Previdian Sensors 2026-07-13 01:45 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.

68

Attempts observed

18

Unique attacker IPs

7

Attacker countries

BR · HK · NL · RU · SG · TW · US

1

Sensors observed

CVE-2026-55255 exploitation attempts over the last 91 days

Daily events observed by Previdian sensors

Updated 11 Oct 2026

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13 Jul 1 Aug 20 Aug 8 Sep 11 Oct

First observed 13 Jul 2026 · Last observed 30 Sep 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
1
2
0

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

Scanner coverage

No scanner integrations recorded yet.

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.

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Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.4 High

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

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

EPSS

0.9%

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

Weaknesses

Authorization Bypass Through User-Controlled Key CWE-639

Recent mention · All CISA Advisories

CISA Adds Three Known Exploited Vulnerabilities to Catalog

CISA has added three new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation. CVE-2026-48908 JoomShaper SP Page Builder Unrestricted Upload of File with Dangerous Type Vulnerability CVE-2026-55255 Langflow...

Read full advisory

Potential Proof of Concepts

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

Langflow’s /api/v1/responses endpoint contains an IDOR that lets any authenticated user execute another user’s flow by supplying the victim’s flow UUID.

pruva · Created 2026-07-08 04:49:10 UTC

Severity: CRITICAL | CVE: CVE-2026-55255 | Package: langflow (pip)

https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2

ghsa · Created Unknown · AI assessment 90%

Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow

Timeline

From disclosure to observed exploitation

  1. 01:43 UTC

    Indicators of compromise added (18)

    Indicators of compromise recorded

  2. 01:43 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  3. 04:49 UTC

    Public PoC available

    Public proof-of-concept code published

  4. 19:20 UTC

    KEV confirmed by All CISA Advisories

    Exploitation attested by an external source

  5. 18:20 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  6. 17:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  7. 16:28 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 16:44 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-2026-55255

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-55255",
  "confidence": "Confirmed",
  "cvss_score": 8.4,
  "cvss_estimated": false,
  "epss_score": 0.00887,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 68, "sensors": 1 }
}