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The vulnerability exists in the HTTP/1.x chunked encoding parser of the `vibeio-http` crate, a high-performance HTTP server primitive library for the VibeIO runtime environment. Chunked transfer encoding is a standard HTTP/1.1 mechanism that allows a server to begin sending a response before knowing its total length, by splitting the body into variable-size chunks prefixed with their hexadecimal length.
The parser logic in affected versions (prior to 0.3.2) reads the chunk length from the incoming request and attempts to store it in a `usize` variable. During this process, the code uses the standard `+` operator to perform arithmetic on the length value. An attacker can craft a malicious HTTP/1.x request containing a chunk length set to a value between `usize::MAX – 1` and `usize::MAX` inclusive. These values are dangerously close to the maximum representable value for the `usize` type on the target architecture (typically 2³²-1 on 32-bit systems or 2⁶⁴-1 on 64-bit systems).
When the parser processes this malicious chunk length, the subsequent arithmetic operation causes an integer overflow. In debug builds, this overflow triggers a panic due to Rust’s built-in overflow checking, immediately crashing the server thread. In release builds, where overflow checks are disabled for performance, the overflow leads to an out-of-bounds access when the code later calls `split_to()` on a buffer, resulting in a panic and server crash as well. Both scenarios result in a complete Denial of Service (DoS) as the server process terminates unexpectedly.
The vulnerability is particularly dangerous because it requires no authentication, can be exploited over the network, and the malicious payload is small and easily embedded in a single HTTP request. The fix implemented in version 0.3.2 replaces the unsafe `+` operator with checked_add(), which returns `None` on overflow. The parser now explicitly errors out if the chunk length exceeds usize::MAX - 2, safely rejecting the malformed request without crashing the server. This fix was published on August 24, 2026, and all users are strongly advised to upgrade immediately.
DailyCVE Form:
Platform: VibeIO Runtime
Version: < 0.3.2
Vulnerability: Integer Overflow DoS
Severity: Moderate
date: 2026-08-24
Prediction: 2026-08-25
What Undercode Say:
Check currently installed version cargo tree | grep vibeio-http Update to patched version cargo update -p vibeio-http --precise 0.3.2 Verify the fix in Cargo.toml grep "vibeio-http" Cargo.toml
Exploit: (Educational Purposes!)
// Malicious chunk length payload in raw HTTP/1.1 request let malicious_request = "POST / HTTP/1.1\r\n\ Host: target.com\r\n\ Transfer-Encoding: chunked\r\n\r\n\ FFFFFFFFFFFFFFFE\r\n\ A\r\n\ 0123456789\r\n\ 0\r\n\r\n"; // The chunk length "FFFFFFFFFFFFFFFE" (hex) equals usize::MAX - 1 on 64-bit // Triggering integer overflow in affected versions
Protection:
Upgrade to `vibeio-http` version 0.3.2 or later immediately. If immediate upgrade is not possible, implement a reverse proxy or WAF that validates and rejects chunked transfer encoding requests with excessively large chunk length values before they reach the vulnerable server. Monitor server logs for crash patterns and unexpected terminations.
Impact:
Unauthenticated remote attackers can crash the server with a single HTTP request, causing complete service disruption. All applications using affected versions of `vibeio-http` (0.1.0 through 0.3.1) are vulnerable. The crash affects both debug and release builds, making all deployment environments susceptible. No data breach or code execution is possible, but the availability impact is total as the server process terminates and requires manual restart or orchestration auto-recovery.
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Sources:
Reported By: github.com
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