CVE-2026-25899
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 49% of all known CVEs.
References
Related Vulnerabilities
Other CWE-789 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-30522 | High | 7.5 | 90% | - | Fix |
| CVE-2025-27533 | High | 7.5 | 9.0% | - | Fix |
| CVE-2017-7651 | High | 7.5 | 5.1% | - | Fix |
| CVE-2026-49975 | High | 7.5 | 4.2% | - | Fix |
| CVE-2021-31811 | Medium | 5.5 | 3.6% | - | - |
| CVE-2021-27906 | Medium | 5.5 | 3.3% | - | Fix |
Common questions
How do I fix CVE-2026-25899?
Upgrade fiber to 3.1.0 or later.
Is CVE-2026-25899 being actively exploited?
Not that we know of. CVE-2026-25899 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.63% is the estimated probability that it will be exploited in the next 30 days. That is higher than 49% of all scored CVEs.
How severe is CVE-2026-25899?
CVE-2026-25899 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-25899 affect?
Published advisories record a fix for fiber (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-25899
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-02-25.