CVE-2026-15341
CRITICALCVE-2026-15341 is a critical-severity (CVSS 9.8) Improper Authentication vulnerability. O3 Security confirms whether CVE-2026-15341 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
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()`…
Description
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-15341 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-15341 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-15341. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-15341 in your dependencies?
O3 detects CVE-2026-15341 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.