Langflow /api/v1/responses Cross-Tenant IDOR
CVE-2026-55255 is a critical insecure direct object reference vulnerability in Langflow affecting versions prior to 1.9.2. The flaw is in the POST /api/v1/responses endpoint, where the supplied model field can reference a flow UUID. Langflow resolves flows by UUID via get_flow_by_id_or_endpoint_name without enforcing a user_id ownership check on that code path. As a result, an authenticated attacker who knows a victim’s flow ID can submit requests that cause execution of flows belonging to another user. Available reporting also indicates the endpoint_name lookup path enforces ownership checks, and only the UUID-based resolution path is vulnerable. In observed exploitation, attackers first enumerated flow IDs via GET /api/v1/flows/ and then replayed those IDs to /api/v1/responses to trigger victim flows.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A critical cross-tenant IDOR vulnerability in Langflow that allows an authenticated attacker to execute another user's flow by supplying its UUID to the /api/v1/responses endpoint, potentially exposing the victim's embedded credentials in multi-tenant environments.
An IDOR vulnerability in Langflow's /api/v1/responses endpoint that allows an authenticated attacker to access and execute another user's flow by supplying the victim's flow ID.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.