HTTP 401 means the server rejected unproven credentials
Original title: HTTP 401 Unauthorized: What It Means and How to Fix It
Sucuri covers WordPress, server, and API causes, and when a sudden wave of 401s can indicate compromise.
Sucuri explains that HTTP 401 Unauthorized means the server understood a request but did not receive acceptable credentials. Common causes include wrong or expired credentials, stale sessions, server-level password rules, plugin conflicts, proxies or CDNs, and API authentication mismatches. The post also says injected code or unauthorized authentication changes can produce a sudden wave of 401s.
Unconfirmed: The excerpt cuts off before explaining how malware would change authentication.
- A proper 401 should include a WWW-Authenticate header naming the expected scheme.
- Wrong passwords, expired tokens, and stale cookies are the most common causes.
- Plugins, proxies, CDNs, and caching can return intermittent 401s.
- The excerpt says malware changing authentication is a less considered cause.
From the original article
13 min read at blog.sucuri.net
You load your site, or visit an API endpoint your app relies upon, and instead of a page you find a brief, unhelpful message: 401 Unauthorized. Sometimes a browser password box appears. Other times, a blank white page presents only that number.
By Sucuri · blog.sucuri.net
A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.