CVE-2026-18329

Description NGINX JavaScript (njs) and QuickJS (qjs) engines have a vulnerability when a js_access handler performs asynchronous request body processing and an exception is thrown during asynchronous access-control evaluation before an explicit access denial is returned. An unauthenticated attacker can exploit this vulnerability by sending a crafted HTTP request that triggers an error condition in the access validation logic. This may cause the js_access phase to fail open, allowing the request to proceed instead of being denied, resulting in an authentication or authorization bypass and unauthorized access to protected resources. Impact This vulnerability may allow remote attackers to bypass js_access controls. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVSS v3 8.2 HIGH

8.2^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://my.f5.com/manage/s/article/K000162599

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-02 16:17

Updated : 2026-09-03 16:37

NVD link : CVE-2026-18329

Mitre link : CVE-2026-18329

CVE.ORG link : CVE-2026-18329

JSON object : View

Products Affected

No product.

CWE

CWE-636

Not Failing Securely ('Failing Open')

{"id": "CVE-2026-18329", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-18329", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-02T17:56:50.319435Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "f5sirt@f5.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.2, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 4.2, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "f5sirt@f5.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.8, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "LOW", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "f5sirt@f5.com", "affectedData": [{"vendor": "F5", "modules": ["ngx_http_js_module"], "product": "NGINX JavaScript", "versions": [{"status": "affected", "version": "1.0.0", "lessThan": "1.0.1", "versionType": "custom"}, {"status": "affected", "version": "0.9.9", "lessThan": "*", "versionType": "custom"}], "defaultStatus": "unknown"}]}], "published": "2026-09-02T16:17:14.917", "references": [{"url": "https://my.f5.com/manage/s/article/K000162599", "source": "f5sirt@f5.com"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Secondary", "source": "f5sirt@f5.com", "description": [{"lang": "en", "value": "CWE-636"}]}], "descriptions": [{"lang": "en", "value": "Description\n\nNGINX JavaScript (njs)\u00a0and QuickJS (qjs) engines\u00a0have a vulnerability when a js_access handler performs asynchronous request body processing and an exception is thrown during asynchronous access-control evaluation before an explicit access denial is returned. An unauthenticated attacker can exploit this vulnerability by sending a crafted HTTP request that triggers an error condition in the access validation logic. This may cause the js_access phase to fail open, allowing the request to proceed instead of being denied, resulting in an authentication or authorization bypass and unauthorized access to protected resources.\n\nImpact\n\nThis vulnerability may allow remote attackers to bypass js_access controls. There is no control plane exposure; this is a data plane issue only.\n\n\n\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated."}], "lastModified": "2026-09-03T16:37:52.170", "sourceIdentifier": "f5sirt@f5.com"}