Advisory details:
github_osv / GHSA-2x8m-83vc-6wv4
| Advisory ID | github_osv/GHSA-2x8m-83vc-6wv4 |
| Aliases |
CVE-2026-41272
|
| Summary | Flowise: SSRF Protection Bypass (TOCTOU & Default Insecure) ### Summary The core security wrappers (secureAxiosRequest and secureFetch) intended to prevent Server-Side Request Forgery (SSRF) contain multiple logic flaws. These flaws allow attackers to bypass the allow/deny lists via DNS Rebinding (Time-of-Check Time-of-Use) or by exploiting the default configuration which fails to enforce any deny list. ### Details The flaws exist in `packages/components/src/httpSecurity.ts`. Default Insecure: If process.env.HTTP_DENY_LIST is undefined, checkDenyList returns immediately, allowing all requests (including localhost). DNS Rebinding (TOCTOU): The function performs a DNS lookup (dns.lookup) to validate the IP, and then the HTTP client performs a new lookup to connect. An attacker can serve a valid IP first, then switch to an internal IP (e.g., `127.0.0.1`) for the second lookup. ### PoC Ensure `HTTP_DENY_LIST` is unset (default behavior). Use any node utilizing secureFetch to access `http://127.0.0.1`. Result: Request succeeds. #### Scenario 2: DNS Rebinding Attacker controls domain attacker.com and a custom DNS server. Configure DNS to return `1.1.1.1` (Safe IP) with TTL=0 for the first query. Configure DNS to return `127.0.0.1` (Blocked IP) for subsequent queries. Flowise validates `attacker.com` -> `1.1.1.1` (Allowed). Flowise fetches `attacker.com` -> `127.0.0.1` (Bypass). Run the following for manual verification ```ts // PoC for httpSecurity.ts Bypasses import * as dns from 'dns/promises'; // Mocking the checkDenyList logic from Flowise async function checkDenyList(url: string) { const deniedIPs = ['127.0.0.1', '0.0.0.0']; // Simplified deny list logic if (!process.env.HTTP_DENY_LIST) { console.log(\"⚠️ HTTP_DENY_LIST not set. Returning allowed.\"); return; // Vulnerability 1: Default Insecure } const { hostname } = new URL(url); const { address } = await dns.lookup(hostname); if (deniedIPs.includes(address)) { throw new Error(`IP ${address} is denied`); } console.log(`✅ IP ${address} allowed check.`); } async function runPoC() { console.log(\"--- Test 1: Default Configuration (Unset HTTP_DENY_LIST) ---\"); // Ensure env var is unset delete process.env.HTTP_DENY_LIST; try { await checkDenyList('http://127.0.0.1'); console.log(\"[PASS] Default config allowed localhost access.\"); } catch (e) { console.log(\"[FAIL] Blocked:\", e.message); } console.log(\"\ --- Test 2: 'private' Keyword Bypass (Logic Flaw) ---\"); process.env.HTTP_DENY_LIST = 'private'; // User expects this to block localhost try { await checkDenyList('http://127.0.0.1'); // In real Flowise code, 'private' is not expanded to IPs, so it only blocks the string \"private\" console.log(\"[PASS] 'private' keyword failed to block localhost (Mock simulation).\"); } catch (e) { console.log(\"[FAIL] Blocked:\", e.message); } } runPoC(); ``` ### Impact Confidentiality: High (Access to internal services if protection is bypassed). Integrity: Low/Medium (If internal services allow state changes via GET). Availability: Low. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 6.4 |
| Risk | 3.2 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| System | Score | Found at |
|---|---|---|
| cvssv3 | 7.1 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-2x8m-83vc-6wv4/GHSA-2x8m-83vc-6wv4.json |
| generic_textual | HIGH |
| Reference id | Reference type | URL |
|---|---|---|
| https://github.com/FlowiseAI/Flowise | ||
| https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-2x8m-83vc-6wv4 | ||
| CVE-2026-41272 | https://nvd.nist.gov/vuln/detail/CVE-2026-41272 |
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/2026-04-23T20:18:28Z/
Decision: Track*
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/41xxx/CVE-2026-41272.json
Source Advisory: vulnrichment/CVE-2026-41272
[{'Exploitation': 'poc'},
{'Automatable': 'no'},
{'Technical Impact': 'total'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]