Fiber
CVE-2026-25899
HIGH
GHSA-2mr3-m5q5-wgp6
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
4DescriptionGitHub Advisory
Fiber is an Express inspired web framework written in Go. In versions on the v3 branch prior to 3.1.0, the use of the fiber_flash cookie can force an unbounded allocation on any server. A crafted 10-character cookie value triggers an attempt to allocate up to 85GB of memory via unvalidated msgpack deserialization. No authentication is required. Every GoFiber v3 endpoint is affected regardless of whether the application uses flash messages. Version 3.1.0 fixes the issue.
AnalysisAI
Unbounded memory allocation in Fiber v3 (prior to 3.1.0) allows unauthenticated remote attackers to trigger denial of service by sending a malicious fiber_flash cookie that forces deserialization of up to 85GB of memory. All v3 endpoints are vulnerable regardless of flash message usage, and public exploit code exists. No patch is currently available.
Technical ContextAI
Affects Fiber. Fiber is an Express inspired web framework written in Go. In versions on the v3 branch prior to 3.1.0, the use of the fiber_flash cookie can force an unbounded allocation on any server. A crafted 10-character cookie value triggers an attempt to allocate up to 85GB of memory via unvalidated msgpack deserialization. No authentication is required. Every GoFiber v3 endpoint is affected regardless of whether the application uses flash messages. Version 3.1.0 fixes the issue.
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
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Same technique Deserialization
View allVendor StatusVendor
SUSE
Severity: High| Product | Status |
|---|---|
| openSUSE Leap 15.6 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | Fixed |
| openSUSE Leap 15.5 | Fixed |
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External POC / Exploit Code
Leaving vuln.today