Vulnerability · Published Aug 5, 2025 · Assigned by GitHub_M
CVE-2025-54801Fiber Susceptible to Crash via `BodyParser` Due to Unvalidated Large Slice Index in Decoder
High 8.7
In plain English
A high-severity security flaw in fiber from gofiber. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/gofiber/fiber/v2 | 2.52.9 | GHSA-qx2q-88mx-vhg7 |
| Go | github.com/gofiber/fiber/v2 | 2.52.9 | GO-2025-3845 |
Affected products (as reported)
Weakness: CWE-789 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N