IBM Langflow OSS CVE-2026-104316

Requires an authenticated account on the target Langflow OSS instance (PR:L) and knowledge or enumeration of another user's running background job identifier; exploitation is then a single HTTP request against the job-cancellation function, which lacks a flow-level ownership/permission check. Applies to default configurations of versions 1.0.0 through 1.12.3. No user interaction is required (UI:N). The primary limiting factor is the authentication requirement - the attacker must already be a valid user - so the realistic exposure is multi-tenant or shared deployments where distrusted users share an instance; a single-user/isolated deployment has little practical risk. Impact is confined to availability of in-progress jobs (no data disclosure or modification).

This is a medium-severity authorization flaw (CVSS 6.5) whose signals point to a real but bounded operational issue rather than an urgent security emergency. The provided CVSS vector (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) shows remote, low-complexity exploitation by an already-authenticated low-privileged user, with no confidentiality or integrity impact - the entire weight is on availability. There is no EPSS score, no CISA KEV listing, and no PoC reference in the input, so there is no evidence of active exploitation or published exploit code; exploitation status is 'no public exploit identified at time of analysis.' The vendor-assigned priority is 'this_month' (not act_now/emergency), which is consistent with a patch being available and no in-the-wild activity. One point of tension worth flagging: the input rates availability as A:H, but the described impact is cancellation of a single victim's in-progress workflow job - a limited, transient loss of compute work rather than a full service outage, so A:H arguably overstates the per-request impact (though an attacker scripting repeated cancellations of all users' jobs could approach a sustained denial condition). Net: a legitimate multi-tenant access-control bug warranting patching on a normal cycle, not a drop-everything priority, and the absence of EPSS/KEV/PoC data should be treated as missing signal, not as evidence of safety.

On a shared or multi-tenant Langflow OSS instance, an attacker holding a valid low-privileged account identifies the run/job identifier of another user's executing background workflow and sends a single crafted HTTP request to cancel it. Because the endpoint performs no flow-level permission check (CWE-285), the victim's in-progress job is terminated and its compute work is lost. No public exploit code is identified at time of analysis; exploitation requires only an authenticated session and a reachable job identifier.