CVE-2025-13166: The SMS OTP flow fails to adequately handle error messages, allowing an attacker to infer the existence of registered user accounts based on the responses recei

The SMS OTP flow fails to adequately handle error messages, allowing an attacker to infer the existence of registered user accounts based on the responses recei

The SMS OTP flow fails to adequately handle error messages, allowing an attacker to infer the existence of registered user accounts based on the responses received during the OTP initiation process. This weakness can be exploited by an attacker to discover valid usernames within the system. The impact is amplified for accounts that have not configured a mobile number, as the enumeration is specifically tied to this condition. The discovery of these usernames can facilitate subsequent brute force attacks, social engineering attempts, and information leakage, potentially leading to reputational damage, loss of customer trust, and regulatory non-compliance.

Description from the National Vulnerability Database, published by ed10eef1-636d-4fbe-9993-6890dfa878f8

What it means for a small business

If your business uses WSO2 Identity Server, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.27%, higher than 19% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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