How severe is CVE-2026-25899?

CVE-2026-25899 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-25899 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25899?

CVE-2026-25899 affects Gofiber Fiber. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25899?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-25899 have an EU (EUVD) identifier?

Yes. CVE-2026-25899 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8566.

When was CVE-2026-25899 published?

CVE-2026-25899 was published on 2026-02-24 and last updated on 2026-06-17.

CVE-2026-25899

CVE-2026-25899 is a high-severity vulnerability in Gofiber Fiber with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8566
Weakness: CWE-770
Affected product: Gofiber Fiber
Published: 2026-02-24
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-25899?: CVE-2026-25899 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-25899 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25899?: CVE-2026-25899 affects Gofiber Fiber. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25899?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-25899 have an EU (EUVD) identifier?: Yes. CVE-2026-25899 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8566.
When was CVE-2026-25899 published?: CVE-2026-25899 was published on 2026-02-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:*

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