CVE-2026-25899
Fiber is Vulnerable to Denial of Service via Flash Cookie Unbounded Allocation
Description
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.
INFO
Published Date :
Feb. 24, 2026, 10:16 p.m.
Last Modified :
Feb. 25, 2026, 8:31 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update Fiber to version 3.1.0 or later.
- Apply any relevant security patches provided by the vendor.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-25899.
| URL | Resource |
|---|---|
| https://github.com/gofiber/fiber/releases/tag/v3.1.0 | Release Notes |
| https://github.com/gofiber/fiber/security/advisories/GHSA-2mr3-m5q5-wgp6 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-25899 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-25899
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-25899 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-25899 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Feb. 25, 2026
Action Type Old Value New Value Added CWE CWE-770 Added CPE Configuration OR *cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:* versions from (including) 3.0.0 up to (excluding) 3.1.0 Added Reference Type GitHub, Inc.: https://github.com/gofiber/fiber/releases/tag/v3.1.0 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/gofiber/fiber/security/advisories/GHSA-2mr3-m5q5-wgp6 Types: Exploit, Vendor Advisory -
New CVE Received by [email protected]
Feb. 24, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-789 Added Reference https://github.com/gofiber/fiber/releases/tag/v3.1.0 Added Reference https://github.com/gofiber/fiber/security/advisories/GHSA-2mr3-m5q5-wgp6