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Vulnerabilities

Vulnerability · CVE-2026-25899

Fiber is an Express inspired web framework written in Go.

Published Feb 24, 2026 · catalog updated Jun 17, 2026 · Fiber is an Express

Check if you run it

No confirmed exploitation is on record for CVE-2026-25899. EPSS is 0.65%. Act only if a listed version of Fiber is an Express is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Fiber is an Express).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.65%
Remediation
Advisory link
Affected products
cpe gofiber/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 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe gofiber/fiberversion unspecified

How to fix CVE-2026-25899

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-25899. EPSS is 0.65%. Act only if a listed version of Fiber is an Express is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-770: Allocation of Resources Without Limits or Throttling; CWE-789. EPSS 0.65%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 24, 2026 · NIST NVD

    Detected

    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 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 a

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 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 a

Sources

  • CVE.orgVulnerability recordCVE-2026-25899

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-25899

    30-day exploitation probability 0.6%

    first.org
  • NIST NVDVulnerability recordCVE-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 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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.