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Fiber CVE-2026-25899

HIGH
Memory Allocation with Excessive Size Value (CWE-789)
2026-02-24 security-advisories@github.com GHSA-2mr3-m5q5-wgp6
Deserialization Fiber Suse
7.5
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
HIGH
qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
Analysis Generated
Mar 12, 2026 - 21:55 vuln.today
PoC Detected
Feb 25, 2026 - 20:31 vuln.today
Public exploit code
CVE Published
Feb 24, 2026 - 22:16 nvd
HIGH 7.5

DescriptionGitHub Advisory

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.

AnalysisAI

Unbounded memory allocation in Fiber v3 (prior to 3.1.0) allows unauthenticated remote attackers to trigger denial of service by sending a malicious fiber_flash cookie that forces deserialization of up to 85GB of memory. All v3 endpoints are vulnerable regardless of flash message usage, and public exploit code exists. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Send HTTP request with crafted fiber_flash cookie
Exploit
Trigger unvalidated msgpack deserialization
Execution
Allocate unbounded memory
Impact
Exhaust server resources and crash service
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Vulnerability AssessmentAI

Exploitation GoFiber v3 prior to 3.1.0 with any HTTP endpoint exposed. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 7.5 (HIGH). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker without authentication could exploit this vulnerability to compromise the affected system.
Remediation Monitor vendor advisories for a patch. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: inventory all systems running Fiber v3 and assess exposure; implement WAF rules to block or sanitize fiber_flash cookies; notify application teams. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

Vendor StatusVendor

SUSE

Severity: High
Product Status
openSUSE Leap 15.6 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP5 Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP6 Fixed
openSUSE Leap 15.5 Fixed

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CVE-2026-25899 vulnerability details – vuln.today
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