CVE-2026-55255: Langflow Authorization Bypass Through User-Controlled Key Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on , 14 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 0.9%
EPSS score, percentile 59.2 of all scored records
- How severe?
- 8.4 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline . Apply mitigations in accordance with vendor instructions … Full text
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- < 1.9.1
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
What to do
Required action, set by CISA
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CISA due date for this action: .
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-55255
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | < 1.9.1 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
About this vulnerability
Langflow contains an authorization bypass through user-controlled key vulnerability which allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.
Summary: CISA's KEV catalog, as of .
- CISA added CVE-2026-55255 to its Known Exploited Vulnerabilities (KEV) catalog on 7 Jul 2026.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 10 Jul 2026.
- The CVE record was published on 23 Jun 2026, 14 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 8.4 (High), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.9% (percentile 59.2), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.
Description
Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.
Weakness
- CWE-639: Authorization Bypass Through User-Controlled Key
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| Added to CISA KEV | |
| CISA due date for the required action | |
| CVE record last updated |
References
- https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
- https://github.com/langflow-ai/langflow/pull/12832
- https://github.com/langflow-ai/langflow/commit/2c9f498d664a3c32698b57d7c5e752625291060e
More exploited Langflow vulnerabilities
- CVE-2026-0770: Langflow Inclusion of Functionality from Untrusted Control Sphere Vulnerability
- CVE-2025-34291: Langflow Origin Validation Error Vulnerability
- CVE-2026-33017: Langflow Code Injection Vulnerability
- CVE-2025-3248: Langflow Missing Authentication Vulnerability