Patchfirst
CVE-2026-55255 KEVPublic exploit High · 8.4 EPSS 0.9%

Langflow Authorization Bypass Through User-Controlled Key Vulnerability

Langflow · Langflow

Summary

Langflow, a tool for building and deploying AI-powered agents and workflows, contains an insecure direct object reference in its /api/v1/responses endpoint before version 1.9.1, which is the affected component. An authenticated attacker can execute flows belonging to other users by supplying the victim's flow ID in the request, so exploitation requires only a valid account over network access and no user interaction.

Official description · NVD

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.

Breakdown
65.7 / 100
Exploited
Yes, in CISA KEV
Reports
0
Tactics
2/15

How an attack unfolds

Based on mappings. Select a step to see the evidence.
  1. How attackers get in

  2. What they do

First seen exploited 3 days after disclosure.

  1. Disclosedday 0
  2. First seen exploitedVulnCheck KEV evidence+3 days
  3. Added to CISA KEVEU database agrees+14 days

CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.

techniques

2 , grouped by in kill-chain order, 2 cited passages 2

Initial AccessTA0001

Exploit Public-Facing Application T1190 Medium
AI mapping from the description · how it is exploited

remote exploit of public-facing API endpoint

allows an authenticated attacker to execute any flow belonging to another user
From the official description (NVD) Original (opens in a new tab) ↗

CollectionTA0009

Data from Local System T1005 Medium
AI mapping from the description · primary impact

accesses other users' flows and data

execute any flow belonging to another user by specifying the victim's flow ID
From the official description (NVD) Original (opens in a new tab) ↗

Detection

0 rules for this CVE · 163 general rules for its techniques

Rules for this CVE

0 that reference CVE-2026-55255 directly.

CVE-specific rules are not available in this build. Search SigmaHQ ↗

Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.

Am I affected? What do I upgrade to?

From GitHub Security Advisories and OSV

1 package in 1 ecosystem. Main package: langflow.

Upgrade to 1.10.3 or later

Fixes this CVE and 12 other known vulnerabilities in this package (CVE-2024-37014, CVE-2025-3248, +10).

pippip install "langflow>=1.10.3"

First fixed in 1.9.2 for CVE-2026-55255.

Affected versions, by release line

If you runUpgrade to
All versions before 1.9.21.10.3first fix for this CVE: 1.9.2
All versions before 1.9.11.10.3first fix for this CVE: 1.9.1

“Up to” means the second version is the fix and is not affected.

Check your lockfile against all CVEs

What security researchers reported

Not named in any threat report yet

Also mentioned in 50 community threat pulses (AlienVault OTX)

Weaker evidence

Pulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.

References

5 links, grouped by NVD tag (1 duplicate merged)
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