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NVD / CVE Program· CNA GitHub_M

CVE-2026-55255: Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow

Noroxi assessment

Priority: This week (action score 63/100)

  • CISA has confirmed exploitation in the wild (Jul 7, 2026). Remediation deadline for US federal agencies: Jul 10, 2026.
  • Probability of exploitation in the next 30 days: 0.88% (FIRST EPSS); higher than 59.1% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: langflow-ai langflow 1.9.1.

Don’t wait for the next maintenance window. Upgrade to langflow-ai langflow 1.9.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

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.

HighCVSS 8.4 · v3.1KEVWeaponized Fix available
Published
Jun 23, 2026
Updated
Oct 25, 2026
EPSS
0.8% · 59th percentile

Report tools

JSON

Action score

63

This week

Don’t wait for the next maintenance window.

CVSS
33 / 40 · 8.4 / 10
CISA KEV
30 / 30 · Listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
8.4
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Jul 7, 2026. That signals real attacks, not theory.

Remediation deadline for US federal agencies: Jul 10, 2026.

Get told when this record changes

  • In CISA KEV: exploitation in the wild confirmed
  • Weaponized exploit exists
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-55255

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
langflowlangflow

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • langflow langflowbefore 1.9.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • langflow-ai langflow

    • < 1.9.1affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPIlangflowbefore 1.9.11.9.1
PyPIlangflowbefore 1.9.21.9.2

Same product

langflow: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-3248Langflow < 1.3.0 Unauthenticated RCE via /api/v1/validate/codeKEV
    99Now
  • CVE-2026-33017Langflow has Unauthenticated Remote Code Execution via Public Flow Build EndpointKEV
    96Now
  • CVE-2025-34291Langflow <= 1.6.9 CORS Misconfiguration to Token Hijack & RCEKEV
    95Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-48519Jun 23, 2026 · Langflow: Unauthenticated RCE in Shareable Playgrounds
    38Monitor
  • ← EarlierCVE-2026-48520Jun 23, 2026 · Langflow: Unauthenticated Shareable Playground arbitrary local or S3 file read
    24Monitor
  • Later →CVE-2026-55423Jun 23, 2026 · Langflow: Logout button does not clear session
    24Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
langflow-ai langflow1.9.1 · descriptionVendor (CNA)
PyPI:langflow1.9.1Package registry (OSV)
PyPI:langflow1.9.2Package registry (OSV)

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-06-30

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+6 d
  3. CISA KEV+13 d
  4. TodayOct 29, 2026+128 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-101407 days apartCross-Tenant API Key Reuse and Billing Fraud in Langflow Voice Mode Subsystem
    38Monitor
  • CVE-2026-337600 days apartLangflow: IDOR/BOLA in Monitor API — Missing Ownership Enforcement on 7 Endpoints
    35Monitor
  • CVE-2026-3404688 days apartLangflow: Authenticated Users Can Read, Modify, and Delete Any Flow via Missing Ownership Check
    34Monitor
  • CVE-2026-778712 days apartUnauthenticated Session History Access via Public Flow Execution
    32Monitor
  • CVE-2026-1344524 days apartLangflow is affected by remote code execution, denial of service, path traversal, and exposed credentials due to multiple unauthenticated and insufficiently aut
    32Monitor
  • CVE-2026-654254 days apartMonitor API allows cross-user read of transaction logs and deletion of build data via flow_id
    32Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
low · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
Low

Weakness class (CWE)

CWE-639 · Authorization Bypass Through User-Controlled Key

CVSS vector

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

nvd-secondary

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

The bug in code

The whole CWE-639 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const invoice = await Invoice.findById(req.params.id);res.json(invoice);

Fixed

ts
const invoice = await Invoice.findOne({  id: req.params.id,  ownerId: req.user.id,});if (!invoice) return res.sendStatus(404);res.json(invoice);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records