Home/CVE/Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, unauthenticated users can
CVE
CVE-2026-55450
Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, unauthenticated users can
Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, unauthenticated users can upload any amount of data to the server without any limitations. No need for any prior knowledge, only network access to Langflow.
This can lead to space exhaustion on the server. In addition, in the response, the absolute path of the uploaded file is reported to the attacker, which is an information leak that can assist in chaining other primitives. This vulnerability is fixed in 1.9.1.
CRITICAL · CVSS 9.3
Schedule remediation
- CVSS base score ≥ 7.0
No Sigma yet — build one →
YARA rules0
Look this up elsewhere - one-click external pivots
▸
How to read a CVE - triage first, then detect and patch
This page is every public fact about CVE-2026-55450, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.
Triage: should I act now? Four signals, and they are not interchangeable:
CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked.
EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal.
CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score.
Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.
How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.
Then what - two workflows:
Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits.
PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.
Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).
EPSS exploitation probability
n/a
No EPSS score in our data for this CVE. EPSS is published daily for scored CVEs - a very new, reserved, or rejected CVE may not have one yet.
CVSS metric silhouette
shape grows toward worst-case
SSVC triage
No SSVC vulnrichment for this CVE. CISA's Vulnrichment program scores newer CVEs (~2024 onwards) plus selected older critical ones. Use the EPSS probability + KEV status to triage instead.
CVSS vector breakdown
Exploitability - how they get in
Attack Vector
Network
Adjacent
Local
Physical
Attack Complexity
Low
High
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Impact - what breaks
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:H◆
ATT&CK techniques
1Techniques this CVE enables. Pills with a solid outline are high confidence - named directly in ATT&CK or Nuclei, or human-curated by CTID; the rest are inferred from the weakness type using MITRE's CVE Mapping Methodology and the CWE → CAPEC chain. Broad, generic-weakness guesses are filtered out. A small N× marks a technique that N independent sources agree on.
▤ Build a SIEM detection for these techniques▤
CAPEC attack patterns
12Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.
CAPEC-CAPEC-116 · Excavation CAPEC-CAPEC-12 · Choosing Message Identifier CAPEC-CAPEC-13 · Subverting Environment Variable Values CAPEC-CAPEC-147 · XML Ping of the Death CAPEC-CAPEC-166 · Force the System to Reset Values CAPEC-CAPEC-169 · Footprinting CAPEC-CAPEC-216 · Communication Channel Manipulation CAPEC-CAPEC-22 · Exploiting Trust in Client CAPEC-CAPEC-224 · Fingerprinting CAPEC-CAPEC-227 · Sustained Client Engagement CAPEC-CAPEC-285 · ICMP Echo Request Ping CAPEC-CAPEC-287 · TCP SYN Scan
⬡
Weakness Classification
▤
Affected Packages
1Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
PyPI
langflow
CRITICAL
fixed in 1.9.1
▤
Related CVEs
8CVEs linked to this one by a shared weakness (CWE) or affected product - joins on data already in the engine, with the reason shown per row.
CVE-1999-0059
IRIX fam service allows an attacker to obtain a list of all files on the server.
same CWE-200
HIGH
CVE-1999-0524
ICMP information such as (1) netmask and (2) timestamp is allowed from arbitrary...
same CWE-200
MEDIUM
CVE-1999-1136
Vulnerability in Predictive on HP-UX 11.0 and earlier, and MPE/iX 5.5 and earlie...
same CWE-200
CVE-1999-0453
An attacker can identify a CISCO device by sending a SYN packet to port 1999, wh...
same CWE-200
CVE-2002-1810
D-Link DWL-900AP+ Access Point 2.1 and 2.2 allows remote attackers to access the...
same CWE-306
HIGH
CVE-2004-0213
Utility Manager in Windows 2000 launches winhlp32.exe while Utility Manager is r...
4
same CWE-306
HIGH
CVE-2006-0061
xlockmore 5.13 and 5.22 segfaults when using libpam-opensc and returns the under...
same CWE-306
CRITICAL
CVE-2006-0062
xlockmore 5.13 allows potential xlock bypass when FVWM switches to the same virt...
same CWE-306
CRITICAL
🔗
References & Sources
2Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.