CVE-2026-5027
HighExploitedPublic exploitLangflow - Path Traversal Arbitrary File Write via upload_user_file
Published Mar 27, 2026 · Updated Oct 8, 2026
Key Facts
Patch immediately- CVE-2026-5027 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Langflow.
- It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Jun 8, 2026. Public exploit code is available.
- EPSS estimates a 4.8% probability of exploitation in the next 30 days.
- Fixed versions are available, including Langflow 1.9.0.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
4.8%
Higher than 91.7% of all scored CVEs
Exploited in the wild
Yes
2 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
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 ('../').
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Jun 8, 2026 | n/a | Not reported |
| CIRCL KEV | Jun 10, 2026 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| LangflowLangflow | See advisory | 1.9.0 |
Patched Releases
Langflow
1.9.0
Timeline
Publicly disclosed
Mar 27, 2026
Added to Industry KEV feed
Jun 8, 2026
Added to CIRCL KEV
Jun 10, 2026
Last updated
Oct 8, 2026
Weakness Type
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
References
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5027.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-5027
- exploitExploitDB-52659
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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 ('../').
Affected: Langflow. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Jun 8, 2026.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Langflow 1.9.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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