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TI-2026-20938 Aliases CVE-2026-25899GHSA-2mr3-m5q5-wgp6

Fiber is Vulnerable to Denial of Service via Flash Cookie Unbounded Allocation

Priority LOW 39CWE-789Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-789.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0045 39th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed fiber (gofiber): 3.1.0github.com/gofiber/fiber/v3 (Go): 3.1.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
gofiberfiber3.0.0 to before 3.1.03.1.0Patch availableCNA
—github.com/gofiber/fiber/v3 (Go)before 3.1.03.1.0Patch availableGHSA-2mr3-m5q5-wgp6
  • fiber Vendorgofiber Affected 3.0.0 to before 3.1.0 Fixed in 3.1.0 Patch available CNA
  • github.com/gofiber/fiber/v3 (Go) Vendor— Affected before 3.1.0 Fixed in 3.1.0 Patch available GHSA-2mr3-m5q5-wgp6

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:*3.0.0 to before 3.1.0Vulnerablegofiber
  • cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:* Versions 3.0.0 to before 3.1.0 Vulnerable ·gofiber

Remediation

  • Fix · CNA fiber (gofiber) Fixed in 3.1.0
  • Fix · GHSA-2mr3-m5q5-wgp6 github.com/gofiber/fiber/v3 (Go) Fixed in 3.1.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-25899
  2. 2026-10-03 Alias added: GHSA-2mr3-m5q5-wgp6
  3. 2026-10-20 EPSS moved to the 50th–90th percentile
  4. 2026-10-25 EPSS moved to the below the 50th percentile
  5. 2026-10-25 Priority changed: MEDIUM → LOW

References

Exploit 1

Advisory 1

Other 3

  • TI-2025-34555 Fiber Susceptible to Crash via `BodyParser` Due to Unvalidated Large Slice Index in Decoder CVSS 4.0HIGH 8.7
  • TI-2024-16578 Fiber has Insecure CORS Configuration, Allowing Wildcard Origin with Credentials CVSS 3.1CRITICAL 9.8
  • TI-2025-30446 Fiber panics when fiber.Ctx.BodyParser parses invalid range index CVSS 4.0HIGH 7.7
  • TI-2026-23477 github.com/gofiber/fiber/v3 cache middleware can mix responses across query parameters CVSS 3.1MEDIUM 6.5
  • TI-2026-20922 Fiber has a Denial of Service Vulnerability via Route Parameter Overflow CVSS 4.0MEDIUM 5.5
  • TI-2026-30834 Fiber: XSS in AutoFormat Content Negotiation CVSS 4.0MEDIUM 5.3
See all 16 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences