Advisory details:
github_osv / GHSA-qrpv-q767-xqq2
| Advisory ID | github_osv/GHSA-qrpv-q767-xqq2 |
| Aliases |
CVE-2026-55255
|
| Summary | Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow ## Summary Insecure Direct Object Reference (IDOR) vulnerability in `/api/v1/responses` endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request. ## Details The vulnerability exists in the `get_flow_by_id_or_endpoint_name` helper function in [`src/backend/base/langflow/helpers/flow.py` (lines 399-414)](https://github.com/langflow-ai/langflow/blob/v1.9.0/src/backend/base/langflow/helpers/flow.py#L399C1-L414C67). When a flow is accessed via UUID (flow_id), the function queries the database directly without verifying if the authenticated user owns that flow: ```python # src/backend/base/langflow/helpers/flow.py:399-414 async def get_flow_by_id_or_endpoint_name(flow_id_or_name: str, user_id: str | UUID | None = None) -> FlowRead: async with session_scope() as session: try: flow_id = UUID(flow_id_or_name) # When using UUID, query directly WITHOUT checking user_id flow = await session.get(Flow, flow_id) # ❌ No user_id check! except ValueError: endpoint_name = flow_id_or_name stmt = select(Flow).where(Flow.endpoint_name == endpoint_name) # Only when using endpoint_name is user_id checked if user_id: stmt = stmt.where(Flow.user_id == uuid_user_id) ``` This function is used by the `/api/v1/responses` endpoint (defined in [`src/backend/base/langflow/api/v1/openai_responses.py:589`](https://github.com/langflow-ai/langflow/blob/v1.9.0/src/backend/base/langflow/api/v1/openai_responses.py#L589)). ## PoC (Proof of Concept) ```bash # Attacker (user A) with API_KEY_A tries to execute victim (user B)'s flow curl -X POST "http://localhost:7860/api/v1/responses" \ -H "x-api-key: sk-ATTACKER_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "VICTIM_FLOW_ID", "input_value": "test", "stream": false }' # Returns 200 and executes the victim's flow ``` ## Impact Any authenticated user can: 1. Execute any flow in the system by knowing its flow ID 2. Access potentially sensitive data processed by victim's flows 3. Consume victim's resources ## Fixes Fixed in **PR #12832** (`fix(security): close IDOR in get_flow_by_id_or_endpoint_name`), merged 2026-04-22, released in **Langflow 1.9.1**. The helper normalizes `user_id` once and enforces ownership on **both** lookup branches (UUID *and* `endpoint_name`): ```python flow_id = UUID(flow_id_or_name) flow = await session.get(Flow, flow_id) if flow is not None and uuid_user_id is not None and flow.user_id != uuid_user_id: flow = None # cross-user lookup falls through to the shared 404 ``` Key points: - Cross-user lookups return **404** (not 403), so flow existence is not disclosed via a 403-vs-404 oracle. - `/api/v1/responses` and `/api/v2/workflow` pass `user_id` explicitly, so fixing the helper closes them directly; the `/api/v1/run*` routes were additionally moved from a bare `Depends(get_flow_by_id_or_endpoint_name)` to auth-aware wrapper dependencies (defense in depth). - A malformed `user_id` now fails closed (404 instead of a raw 500). - Webhook routes intentionally keep the unscoped lookup (public by design / explicit ownership check elsewhere). - Regression tests cover the cross-user UUID case and reproduce the original PoC against `/api/v1/responses`. ## Acknowledgements Thanks to the security researchers who responsibly disclosed this vulnerability: * @yzeirnials * @johnatzeropath * @LeftenantZero * @Zwique |
| Status | Published |
| Exploitability | 2.0 |
| Weighted Severity | 7.6 |
| Risk | 10.0 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | 8.4 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-qrpv-q767-xqq2/GHSA-qrpv-q767-xqq2.json |
| generic_textual | HIGH |
| Data source | KEV |
|---|---|
| Date added | July 7, 2026 |
| Description | Langflow contains an authorization bypass through user-controlled key vulnerability which allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request. |
| Required action | Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. |
| Due date | July 10, 2026 |
| Note | https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-55255 |
| Ransomware campaign use | Unknown |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:P/A:N/T:T/P:M/B:A/M:M/D:R/2026-06-23T17:32:36Z/
Decision: Track*
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/55xxx/CVE-2026-55255.json
Source Advisory: vulnrichment/CVE-2026-55255
[{'Exploitation': 'poc'},
{'Automatable': 'no'},
{'Technical Impact': 'total'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]
Vector: SSVCv2/E:A/A:N/T:T/P:M/B:A/M:M/D:A/2026-07-07T17:45:10Z/
Decision: Attend
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/55xxx/CVE-2026-55255.json
Source Advisory: vulnrichment/CVE-2026-55255
[{'Exploitation': 'active'},
{'Automatable': 'no'},
{'Technical Impact': 'total'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]