IBM Langflow OSS: Authorization bypass in message endpoints
Summary
IBM Langflow OSS versions 1.0.0 through 1.12.4 contain three message endpoints that do not verify ownership. Any authenticated user can bulk-delete other users' messages, overwrite message content with malicious prompts, or take over a conversation session by reassigning its session ID. Exploitation requires only a valid Langflow account over the network; the CVSS base score of 8.3 is provided by IBM as CNA.
Affected
- IBM Langflow OSS 1.0.0 through 1.12.4
- Note: the VulDB record lists only 1.12.0 through 1.12.4 as affected; verify against the IBM bulletin.
Fixed in
- IBM recommends upgrading Langflow OSS to version 1.12.5.
- The CVE record also states the issue was fixed in version 1.9.0, which conflicts with the affected range; confirm the fixed version on the IBM bulletin.
Workaround
- No vendor-confirmed workaround specific to this CVE is available.
- Restrict network access to Langflow to trusted networks or place it behind an authenticating reverse proxy until patched.
- Remove unused accounts and review the remaining ones.
Exploitation
- Not marked as known exploited (CISA KEV: no).
- CISA SSVC: exploitation none, automatable no, technical impact total.
- No public proof of concept found in the sources reviewed.
Our recommendation
- Inventory all Langflow OSS instances and their versions, and identify those reachable from the internet or shared with external users.
- Upgrade to the version specified by IBM, currently 1.12.5, after backing up the installation and testing flows.
- Until patched, restrict access and review accounts.
- Review message logs and conversation integrity for unexpected deletions, overwritten content or changed session IDs.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- IBM Security Bulletin: Langflow OSS is affected by multiple vulnerabilities www.ibm.com
- VulDB: CVE-2026-107366 vuldb.com
- VulDB: Langflow OSS entry vuldb.com
- Vulners: PT-2026-117699 security bulletin vulners.com
- Strix: CVE-2026-107366 www.strix.ai
- HOL Guard: CVE-2026-107366 hol.org
- OffSeq Radar: CVE-2026-107366 radar.offseq.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 13:33.
Original description (NVD)
IBM Langflow OSS 1.0.0 through 1.12.4 contains three message endpoints that perform no ownership verification. Any authenticated user can bulk-delete another user's messages, overwrite message content to inject malicious prompts, or hijack an entire conversation session by reassigning its session ID.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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