Quantum Secular Labs / Blog / Advisories
CVE-2026-18886: ServiceNow: Authentication bypass
CVE-2026-18886 is rated critical with a CVSS v4.0 base score of 10.0. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.
Vulnerability description
ServiceNow has remediated an improper access control vulnerability that was identified in the ServiceNow AI platform. This vulnerability could enable an unauthenticated user, in certain circumstances, to create or modify instance data beyond what was intended, resulting in privilege escalation. ServiceNow deployed a security update to hosted instances and ServiceNow provided the update to our partners and self-hosted customers. We are not currently aware of exploitation against ServiceNow instances. We recommend customers promptly apply appropriate updates or upgrade to a patched release if they have not already done so.
Severity breakdown
CVSS v4.0 10.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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
- Attack vector: Network. Exploitable remotely over the network.
- Attack complexity: Low. No special conditions; the attack can be repeated reliably.
- Attack requirements: None. No deployment or execution conditions are needed.
- Privileges required: None. No account or prior access is needed.
- User interaction: None. No action from any user is needed.
- Confidentiality impact (vulnerable system): High. Total loss of confidentiality.
- Integrity impact (vulnerable system): High. Total loss of integrity.
- Availability impact (vulnerable system): High. Total loss of availability.
- Confidentiality impact (subsequent systems): High. Total loss of confidentiality on other systems.
- Integrity impact (subsequent systems): High. Total loss of integrity on other systems.
- Availability impact (subsequent systems): High. Total loss of availability of other systems.
Underlying weakness
CWE-284: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.