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The vulnerability exists within the ALOS HTTP Server framework, specifically in the request parsing logic. When the server receives an HTTP request where the request path begins with a question mark, such as in a GET request with the path simply being “?”, the internal function `sanitizeRequestPath` is called to process this path. Normally, this function is responsible for cleaning and normalizing the request path, such as stripping query strings and ensuring a valid root path. However, a critical flaw arises in its handling of empty paths after the query string is stripped. The function first checks if the length of the original path is zero, but a path of “?” has a length of one, so this check passes. It then calls a helper function, splitPathQuery, to separate the path and query string. For a request path of “?”, this function returns an empty string as the path component. Subsequently, the `sanitizeRequestPath` function attempts to access the first character of this empty string, via p
</code>, without verifying that the string is non-empty. This results in an out-of-bounds index panic, as the string has a length of zero. This panic is not caught by the standard `core.Recovery()` middleware because it occurs deep within the request parsing phase, well before the request reaches any registered handlers or middleware. The panic occurs within the goroutine handling the incoming connection, causing the entire server process to crash abruptly. This crash terminates all active connections and brings the service down. The vulnerability is exploitable over HTTP/1.1, HTTP/2, and also HTTP/3 if the `ListenAndServeQUIC` feature is enabled, as the vulnerable parsing logic is invoked across different protocol implementations. <h2 style="color: blue;">DailyCVE Form:</h2> Platform: ALOS HTTP Server Version: All versions Vulnerability: Denial of Service Severity: Critical date: 2026-06-11 <h2 style="color: blue;">Prediction: 2026-07-11</h2> <h2 style="color: blue;">What Undercode Say:</h2> To test if your server is vulnerable, you can use the following command: [bash] printf 'GET ? HTTP/1.1\r\nHost: x\r\n\r\n' | nc 127.0.0.1 8080
If the server crashes, it is affected by this CVE. The logs will show a panic with the message "panic: runtime error: index out of range
with length 0" originating from `core/utils.go` in the `sanitizeRequestPath` function. <h2 style="color: blue;">Exploit: (Educational Purposes!)</h2> An attacker can send a single crafted HTTP request to crash the server. For example, using <code>curl</code>: [bash] curl -v "http://<target-ip>:<port>/?"
or via netcat:
echo -e "GET ? HTTP/1.1\r\nHost: target\r\n\r\n" | nc <target-ip> <port>
This causes the server to panic and exit, denying service to all legitimate users.
Protection:
Until a patch is released, the primary mitigation is to place a reverse proxy like nginx or HAProxy in front of the ALOS HTTP Server. These proxies can filter out malformed requests, specifically blocking any request line that contains a path starting with a question mark. Additionally, network-level firewalls or WAFs can be configured to drop such requests. The development team should apply the fix from the upstream repository as soon as it is available.
Impact:
This vulnerability allows an unauthenticated remote attacker to perform a Denial of Service (DoS) attack with a single, trivial request. The entire server process crashes, rendering the service unavailable. Since the attack requires only a single packet and no authentication, it is highly efficient and easy to exploit. The default configuration of the ALOS HTTP Server enables HTTP/1.1 and HTTP/2, meaning that all deployments are affected unless shielded by a third-party proxy or a custom network configuration that sanitizes requests beforehand. This severely impacts the availability of any service running on this framework.
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Sources:
Reported By: github.com
Extra Source Hub:
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