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How the CVE Works
The vulnerability occurs in Fiber’s `Ctx.BodyParser` when parsing form data with an excessively large numeric key (e.g., test.18446744073704). The schema decoder attempts to allocate a slice of size `idx + 1` without bounds checking, where `idx` is derived from the numeric key. If `idx` is too large, it causes an integer overflow or excessive memory allocation, leading to a panic or crash. The decoder fails to validate the index before slice creation, making it possible to trigger a denial of service (DoS) via crafted input.
DailyCVE Form
Platform: Fiber (Go)
Version: < v2.50.0
Vulnerability: OOB Slice Allocation
Severity: Critical
Date: 2023-10-15
Prediction: Patch by Nov 2023
What Undercode Say
// Vulnerable Code idx := parts[bash].index value := reflect.MakeSlice(t, idx+1, idx+1) // Crash point
Exploit Command curl -X POST --data 'test.18446744073704' -H 'Content-Type: application/x-www-form-urlencoded'
How Exploit
- Send malicious form data with oversized index.
- Triggers uncontrolled memory allocation.
- Causes application crash/DoS.
Protection from this CVE
- Update Fiber to v2.50.0+.
- Validate slice indices before allocation.
- Implement input sanitization.
Impact
- Remote DoS via crash.
- Memory exhaustion attacks.
- Service disruption.
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Reported By: github.com
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Undercode
