Resource exhaustion in Gofiber Fiber
CVE-2026-25899
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (48.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.002
Affected products
- Gofiber Fiber — versions >= 3.0.0, < 3.1.0
Weakness classification (CWE)
References
- github.com/gofiber/fiber/security/advisories/GHSA-2mr3-m5q5-wgp6 (Exploit, Vendor Advisory)
- github.com/gofiber/fiber/releases/tag/v3.1.0 (Release Notes)
Frequently asked questions
- What is CVE-2026-25899?
- CVE-2026-25899 is a high-severity vulnerability in Gofiber Fiber, classified under CWE-789. CVSS score: 7.5/10. Published 2026-02-24.
- How severe is CVE-2026-25899?
- High severity. CVSS v3 base score is 7.5 out of 10.