NVD / CVE Program· CNA tenable

CVE-2026-5027: Langflow - Path Traversal Arbitrary File Write via upload_user_file

Noroxi assessment

Priority: Plan (action score 47/100)

A ready-made attack module is public (Nuclei); exploiting it takes no special expertise.
Public proof-of-concept code exists (Exploit-DB, GitHub); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 39.9% (FIRST EPSS); higher than 98.6% 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. No special conditions are required; it is repeatable.
According to the record, no fixed version is available yet.

Add it to your regular patch cycle. Update when a fix is released; follow the vendor's advisory.

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 · FIRST EPSS

The 'POST /api/v2/files' endpoint does not sanitize the 'filename' parameter from the multipart form data, allowing an attacker to write files to arbitrary locations on the filesystem using path traversal sequences ('../').

HighCVSS 8.8 · v3.1—Proof of concept No fix recorded

Path traversal

Published: Mar 27, 2026
Updated: Aug 18, 2026
EPSS: 39.9% · 98th percentile
CWE: CWE-22

Report tools

JSON

Action score

Plan

Add it to your regular patch cycle.

CVSS: 35 / 40 · 8.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 12 / 30 · 39.9%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · tenable: 8.8; 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.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Proof of concept exists, no weaponized module
No fixed version yet

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

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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.

Vendor	Product	CPE
langflow	langflow	cpe:2.3:a:langflow:langflow

Affected versions

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

langflow langflowbefore 1.9.0

Versions reported by the vendor

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

langflow-ai langflow
- 0affected

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-2026-5025Mar 27, 2026 · Langflow - Application Logs Exposed to All Authenticated Users
26Monitor
← EarlierCVE-2026-5026Mar 27, 2026 · Langflow - Stored XSS via Malicious SVG Upload
28Monitor
Later →CVE-2026-5022Mar 27, 2026 · Langflow - Missing Authorization on download_image Endpoint
25Monitor

Remediation

Which version to upgrade to

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

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

Exploit-DB entry ×1
Nuclei detection template ×1
Proof-of-concept repository on GitHub ×8

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
Source	Kind	Date
Exploit-DB entry	webapps	2026-08-31
Nuclei detection template	Nuclei template CVE-2026-5027	—
Proof-of-concept repository on GitHub	stars:4	2026-04-02
Proof-of-concept repository on GitHub	stars:0	2026-04-03
Proof-of-concept repository on GitHub	stars:3	2026-04-03
Proof-of-concept repository on GitHub	stars:0	2026-04-03
Proof-of-concept repository on GitHub	stars:0	2026-06-10
Proof-of-concept repository on GitHub	stars:0	2026-06-11
Proof-of-concept repository on GitHub	stars:1	2026-08-21
Proof-of-concept repository on GitHub	stars:0	2026-09-02

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.

PublishedMar 27, 2026
First PoCApr 2, 2026+6 d
TodayNov 2, 2026+220 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.

No commit or PR link among the references.

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-2026-333093 days apartLangflow has an Arbitrary File Write (RCE) via v2 API
43Plan
CVE-2026-334973 days apartLangflow: /profile_pictures/{folder_name}/{file_name} endpoint file reading
40Plan
CVE-2026-4204846 days apartLangflow: Path Traversal in Langflow Knowledge Bases API
39Monitor
CVE-2026-752461 days apartPath Traversal Vulnerability in File Processing Components Allows Unauthorized File System Access and Potential Remote Code Execution
39Monitor
CVE-2026-8859112 days apartPath Traversal in APIRequest Component via Content-Disposition Header
39Monitor
CVE-2026-7667112 days apartPath Traversal Vulnerability in API Request Component Content-Disposition Header Processing
35Monitor

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.
No special conditions are required; it is repeatable.

If successful

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

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

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

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

nvd-secondary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

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

Vulnerable

1const file = path.join(ROOT, req.query.name);
2res.sendFile(file);

Fixed

1const file = path.resolve(ROOT, req.query.name);
2if (!file.startsWith(ROOT + path.sep)) {
3  return res.sendStatus(400);
4}
5res.sendFile(file);

Attack context

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

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

www.tenable.com/security/research/tra-2026-26

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

All records

Noroxi analysis

What does it mean in your environment?

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Data sources and verification

CNA: tenable

CVE.org (CNA)Mar 27, 2026, 3:11 PM UTC
CISA ADPMar 27, 2026, 3:11 PM UTC
NVDAug 18, 2026, 2:00 PM UTC
FIRST EPSSOct 31, 2026, 12:00 AM UTC
Exploit-DBNov 2, 2026, 3:17 AM UTC
NucleiNov 2, 2026, 3:17 AM UTC
PoC-in-GitHubNov 2, 2026, 3:17 AM UTC

Each line is when that source was last processed for this record.