CISA orders federal agencies to patch actively exploited Langflow flaw
CISA has added an actively exploited Langflow vulnerability to its Known Exploited Vulnerabilities (KEV) catalog and directed Federal Civilian Executive Branch (FCEB) agencies to remediate it by Friday. The deadline applies to those federal agencies under the applicable directive; it is not a deadline imposed on private organizations. (CISA KEV catalog; BleepingComputer)
The issue, tracked as CVE-2026-55255, affects Langflow, a platform for building and running AI workflows. BleepingComputer describes it as an authorization flaw that lets an authenticated user access another user’s flow by sending a crafted request to Langflow’s /api/v1/responses endpoint with the victim’s flow UUID (flow_id). The report says exploitation can expose flows and sensitive information they process, and allow an attacker to consume resources on the affected deployment. These are reported potential impacts; they do not establish that every vulnerable instance contains sensitive data or that every exploitation leads to data theft. (BleepingComputer)
What researchers observed
Sysdig’s Threat Research Team reported observing exploitation on June 25. The researchers said the activity sought code execution and delivery of a second-stage implant, which they characterized as a loader or dropper. Sysdig assessed the activity as opportunistic and financially motivated, pointing to computing resources and credentials such as LLM or cloud keys as possible incentives. That is the researchers’ assessment, not a confirmed account of an identified actor’s motive or of data stolen from particular victims. (Sysdig Threat Research Team, as quoted by BleepingComputer)
Langflow’s workflow interface and API allow users to build and run connected processes. The security consequences of unauthorized flow access will depend on what a particular deployment contains and what services or data it can reach. The reporting does not establish that all deployments expose credentials or have the same level of risk.
CISA’s KEV listing and the federal deadline
CISA added CVE-2026-55255 to the KEV catalog and set a Friday remediation deadline for FCEB agencies under Binding Operational Directive 26-04, according to the agency’s listing and BleepingComputer’s report. CISA says KEV entries are known to have been exploited in the wild and directs federal agencies to address listed vulnerabilities within the applicable deadlines. The requirement described here is for covered federal agencies, not private organizations. (CISA KEV catalog; BleepingComputer)
Organizations outside the federal requirement can use the active-exploitation report as a reason to check whether they operate Langflow, identify exposed instances, and consult the project’s release and security guidance for the appropriate fix. The cited reporting does not specify a fixed Langflow version, so administrators should verify the remediation guidance against the project’s own documentation rather than assume a version number.
For an exposed deployment, teams can review available application and network logs for unexpected requests to the affected endpoint, unusual flow access, or unexpected resource use. These are general defensive steps, not additional instructions attributed to CISA. If activity appears suspicious, organizations should follow their incident-response procedures and assess which data and connected services may be in scope.
Earlier Langflow vulnerabilities
Langflow has had other vulnerabilities reported, but they are separate from CVE-2026-55255. CISA’s KEV catalog lists CVE-2025-3248 and CVE-2026-33017 as Langflow vulnerabilities. BleepingComputer reports that CVE-2025-3248 involved missing authentication and that Sysdig linked its exploitation to the JadePuffer ransomware operation, which the researchers said used the flaw to dump Langflow’s PostgreSQL database. The report also identifies CVE-2026-33017 as a code-injection vulnerability. (BleepingComputer)
A separate path-traversal issue, CVE-2026-5027, was reported by SpendLens, which cited VulnCheck researcher Caitlin Condon on exploitation and the ability to write arbitrary files on exposed servers. For further context on federal responses to exploited vulnerabilities, see CISA’s directive covering Langflow and other vulnerabilities. These reports concern distinct vulnerabilities; they are not evidence that CVE-2026-55255 caused the earlier incidents.
The practical response is to establish whether Langflow is deployed, check the project’s current security guidance, and verify that any affected instance has been remediated. Teams should also consider the data and services their workflows can access when assessing exposure. A platform used to build AI workflows still requires the same attention to authorization, patching, and access controls as other software.
Sources: CISA Known Exploited Vulnerabilities catalog; BleepingComputer report; SpendLens report on CVE-2026-5027.