CVE-2020-25574: 
Rust vulnerability analysis and mitigation

An integer overflow vulnerability was discovered in the http crate for Rust, affecting versions before 0.1.20. The vulnerability, identified as CVE-2020-25574, was found in the HeaderMap::reserve() function and was reported on November 16, 2019. This security flaw affects the HTTP header handling functionality in Rust applications using the affected versions of the http crate (RustSec Advisory, NVD).

The vulnerability stems from an integer overflow in the HeaderMap::reserve() function. The function uses usize::next_power_of_two() to calculate increased capacity, which can silently overflow to 0 in release mode when given a sufficiently large number. If the map is not empty when the overflow occurs, the library invokes self.grow(0) and enters an infinite probing loop. The vulnerability has been assigned a CVSS v3.1 base score of 7.5 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (NVD, RustSec Advisory).

The primary impact of this vulnerability is a potential denial of service (DoS) condition. When exploited, it can cause the application to enter an infinite loop, effectively making the service unavailable. The vulnerability affects the availability of the system while not compromising confidentiality or integrity (RustSec Advisory).

The vulnerability can be triggered by an attacker who can control the argument to the reserve() function. The attack requires network access but does not require privileges or user interaction, making it relatively straightforward to exploit (NVD).

The vulnerability was fixed in version 0.1.20 of the http crate. Users should upgrade to this version or later to mitigate the risk. The fix addresses the integer overflow issue in the HeaderMap::reserve() function (RustSec Advisory).