CVE-2026-55255: Langflow Authorization Bypass Through User-Controlled Key Vulnerability
Vulnerability summary
CVE-2026-55255 is a high (CVSS 8.4) vulnerability in Langflow. It is known to be exploited: CISA lists it, first on 07-07-2026. EPSS estimates a 0.89% chance of exploitation in the next 30 days, higher than 58.8% of scored vulnerabilities. 1 public exploit is recorded.
Timeline
- 23-06-2026PublishedVulnerability first disclosed.
- 07-07-2026Added to CISA KEVLangflow Authorization Bypass Through User-Controlled Key Vulnerability
- 10-07-2026CISA remediation dueApply mitigations per vendor instructions.
- 07-10-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · PypiEcosystem advisory · calculated9.9CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:LDiffers
- NVDNIST8.4HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
EPSS trend
Probability
0.89%
Chance of exploitation in the next 30 days
Percentile
59%
Versus all other CVEs
30-day change
0.00 pp
From 0.89% on 21-09-2026
Known exploited
Compare KEV catalogs
CISA KEVListed- Added
- 07-07-2026
- Federal due date
- 10-07-2026
CISA required action
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. github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2 nvd.nist.gov/vuln/detail/CVE-2026-55255
Public exploits
1 foundLangflow
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Langflow1 product
- langflow< 1.9.1
Langflow-ai1 product
- langflow< 1.9.1
PyPI1 product
- langflow< 1.9.1 | < 1.9.2
3 vendors · 3 products
References
8 links- github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2X Refsource CONFIRMWEBEVIDENCEExploitMitigationVendor Advisory
- github.com/langflow-ai/langflow/commit/2c9f498d664a3c32698b57d7c5e752625291060eX Refsource MISCWEBPatch
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-55255Government ResourceWEBUS Government Resource
