Is User Session Synchronizer safe to use?

Laskyr does not give safety verdicts. User Session Synchronizer is closed on wordpress.org. Closed on 2026-08-12 (reason given: Security Issue). Closed plugins get no updates through WordPress, so new security holes will not be fixed for you. Keep User Session Synchronizer on the latest version and remove it if you do not use it.

Which versions of User Session Synchronizer are vulnerable?

Known issues on record (newest first): Authentication bypass (1.4.0 and older); Cross-site request forgery (CSRF) (1.4.0 and older). The full list with sources is on this page.

What should I do if my User Session Synchronizer is out of date?

Take a backup, then update it from Dashboard > Updates (or run wp plugin update user-session-synchronizer). If you cannot update right away, deactivate it until you can. If you think the site was already attacked, run a free scan at https://laskyr.com/scan.

Plugins · user-session-synchronizer · data as of 2026-11-04

Is User Session Synchronizer safe? Known vulnerabilities and latest version

Status: Closed 2026-08-12
Known issues on record: 2
Unpatched in latest: 0

What to do

Replace it. A closed plugin gets no updates through WordPress, so any hole found from now on stays open.
Deactivate and delete it once you have a replacement (Plugins → Deactivate → Delete). Deleting removes its files; deactivating alone leaves them on the server.
If you ran a vulnerable version and something looks off (spam pages, strange admins, redirects), run the free scan, or have us clean it: Emergency Cleanup, $499.

With WP-CLI, once you have a replacement: wp plugin deactivate user-session-synchronizer && wp plugin delete user-session-synchronizer

Check your version

Known vulnerabilities

2 on record, newest first. “Affected” is the version range the source gives; “fixed in” is the version the source names, or (marked *) the first wordpress.org release after the last affected version. 2 record(s) do not state which versions are affected.

critical 9.8 CVE-2026-15341 · published 2026-08-15

Authentication bypass in User Session Synchronizer (1.4.0 and older)

Affected: 1.4.0 and older
Fixed in: unknown
Access needed (per CVSS): No login needed
Range from: CVE record (the advisory publisher) · score by Wordfence

Details from the advisory

The User Session Synchronizer plugin for WordPress is vulnerable to Authentication Bypass leading to Account Takeover in all versions up to, and including, 1.4.0. The `synchronize_session()` function, hooked on `init` and therefore executed on every request, performs no nonce, capability, or shared-secret validation against the attacker-supplied `ussync-key`, `ussync-token`, and `ussync-ref` parameters; when `ussync-key` references an unregistered slot, `get_option()` returns `false` for both the secret key and the domain list, causing the AES-256-CBC encryption key to degrade to the fully predictable `md5('')` and the referer allowlist to collapse to an empty-string match, while the AES IV is unconditionally hard-coded as `md5('another-secret')`. This makes it possible for unauthenticated attackers to supply a crafted request encrypting any known or guessable user email address in the `ussync-ref` parameter, causing the handler to call `wp_set_auth_cookie()` for the matched user and granting full authentication as that user — including administrators — with no prior knowledge of site secrets.

NVD CVE-2026-15341 Wordfence advisory Plugin source

high 7.1 CVE-2025-32612 · published 2025-04-09

Cross-site request forgery (CSRF) in User Session Synchronizer (1.4.0 and older)

Affected: 1.4.0 and older
Fixed in: unknown
Access needed (per CVSS): No login needed; someone on the site has to click a link or open a page
Range from: CVE record (the advisory publisher) · score by Patchstack

Details from the advisory

Cross-Site Request Forgery (CSRF) vulnerability in rafasashi User Session Synchronizer user-session-synchronizer allows Stored XSS.This issue affects User Session Synchronizer: from n/a through <= 1.4.0.

NVD CVE-2025-32612 Patchstack advisory

Recent activity

2026-08-12 — closed on wordpress.org (Security Issue).
2026-08-15 — Authentication bypass disclosed (CVE-2026-15341), fix version not stated.
2025-04-09 — Cross-site request forgery (CSRF) disclosed (CVE-2025-32612), fix version not stated.

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Browse vulnerabilities

Types found in this plugin: Authentication bypass (1) · Cross-site request forgery (CSRF) (1)

Where this data comes from

Version, last update, installs, closure: wordpress.org/plugins/user-session-synchronizer (Plugins API), fetched 2026-11-04.
Vulnerabilities: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Each record links to its CVE page and to the original advisory (Wordfence, Patchstack or WPScan) where there is one. We only list a CVE here when its references or its advisory name this exact plugin, so a few real issues may be missing; none should be about a different plugin. Spot an error? Email Daniel.

Badge for your site or docs (states facts with a date, not a verdict):

<a href="https://laskyr.com/plugins/user-session-synchronizer"><img src="https://laskyr.com/plugins/user-session-synchronizer/badge.svg" alt="User Session Synchronizer vulnerability status"></a>

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