CVE-2025-54801

Fiber is an Express inspired web framework written in Go. In versions 2.52.8 and below, when using Fiber's Ctx.BodyParser to parse form data containing a large numeric key that represents a slice index (e.g., test.18446744073704), the application crashes due to an out-of-bounds slice allocation in the underlying schema decoder. The root cause is that the decoder attempts to allocate a slice of length idx + 1 without validating whether the index is within a safe or reasonable range. If the idx is excessively large, this leads to an integer overflow or memory exhaustion, causing a panic or crash. This is fixed in version 2.52.9.

• https://github.com/gofiber/fiber/commit/e115c08b8f059a4a031b492aa9eef0712411853d
• https://github.com/gofiber/fiber/security/advisories/GHSA-qx2q-88mx-vhg7