CVE-2026-33309

Q: How do I fix CVE-2026-33309?

Upgrade langflow to 1.9.0 or later.

Q: Is CVE-2026-33309 being actively exploited?

Not that we know of. CVE-2026-33309 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 12.4% is the estimated probability that it will be exploited in the next 30 days. That is higher than 96% of all scored CVEs.

Q: How severe is CVE-2026-33309?

CVE-2026-33309 has a CVSS v3 base score of 9.9, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-33309 affect?

Published advisories record a fix for langflow (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

CRITICALEPSS 96th pctl

9.9

CVSS v3

NVD

Description

Langflow is a tool for building and deploying AI-powered agents and workflows. Versions 1.2.0 through 1.8.1 have a bypass of the patch for CVE-2025-68478 (External Control of File Name), leading to the root architectural issue within `LocalStorageService` remaining unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer `ValidatedFileName` dependency. This defense-in-depth failure leaves the `POST /api/v2/files/` endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE). Version 1.9.0 contains an updated fix.

CWE-22Path Traversal CWE-73External Control of File Name or Path CWE-94Code Injection CWE-284Improper Access Control

How to fix

Remediation Available

langflowNVD

Affected:>= 1.2.0, < 1.9.0Fixed in:1.9.0CVE-2026-33309derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

12.36%probability of exploitation in 30 days

96thpercentile

Very high risk: more likely to be exploited than 96% of all known CVEs.

References

Exploit1

github.com

Related Vulnerabilities

Other CWE-22 (Path Traversal) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-23897	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-32315	High	8.6	100%	KEV	Fix
CVE-2022-29464	Critical	9.8	100%	KEV + Ransom	-
CVE-2021-26086	Medium	5.3	100%	KEV	Fix
CVE-2021-22005	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-5902	Critical	9.8	100%	KEV + Ransom	Fix

Common questions

How do I fix CVE-2026-33309?

Upgrade langflow to 1.9.0 or later.

Is CVE-2026-33309 being actively exploited?

Not that we know of. CVE-2026-33309 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 12.4% is the estimated probability that it will be exploited in the next 30 days. That is higher than 96% of all scored CVEs.

How severe is CVE-2026-33309?

CVE-2026-33309 has a CVSS v3 base score of 9.9, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-33309 affect?

Published advisories record a fix for langflow (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-24.