Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-122220 Overview
WPO365 | LOGIN (wpo365-login) plugin before version 45.2 contains an authentication bypass by capture-replay vulnerability caused by a non-functional anti-replay check in Saml2_Service::check_message_id(), which never persists processed SAML message IDs to the wpo365_saml_message_ids transient due to a logic error that returns before saving. Attackers who capture a validly-signed SAMLResponse can replay it to the ACS endpoint repeatedly within its assertion validity window to log in as the victim, including administrators, without detection since the duplicate message ID check never triggers.
Critical Impact
Affected Products
- WPO365 | LOGIN (wpo365-login) plugin: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-04: CVE-2026-122220 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-04: last updated in the NVD database
Technical Details for CVE-2026-122220
Vulnerability Analysis
CVE-2026-122220 is a Security Vulnerability weakness (CWE-294) in WPO365 | LOGIN (wpo365-login) plugin. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction.
With a CVSS base score of 9.1, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The vendor description states: WPO365 | LOGIN (wpo365-login) plugin before version 45.2 contains an authentication bypass by capture-replay vulnerability caused by a non-functional anti-replay check in Saml2_Service::check_message_id(), which never persists processed SAML message IDs to the wpo365_saml_message_ids transient due to a logic error that returns before saving. Attackers who capture a validly-signed SAMLResponse can replay it to the ACS endpoint repeatedly within its assertion validity window to log in as the victim, including administrators, without detection since the duplicate message ID check never triggers.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/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
Detection Methods for CVE-2026-122220
Detection Strategies
- Inventory every instance of WPO365 | LOGIN (wpo365-login) plugin and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward WPO365 | LOGIN (wpo365-login) plugin application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-122220
Immediate Actions Required
- Apply the fixed version of WPO365 | LOGIN (wpo365-login) plugin named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for WPO365 | LOGIN (wpo365-login) plugin.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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