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Pre-Authentication DOS from malformed RESP request

High
madolson published GHSA-93p9-5vc7-8wgr Feb 23, 2026

Package

valkey-server (valkey-io)

Affected versions

=>9.0.0, <= 9.0.2

Patched versions

9.0.3

Description

Impact

A malicious actor with network access to Valkey can cause the system to abort by triggering an assertion.

Details

When processing incoming requests, the Valkey system does not properly reset the networking state after processing an empty request. A malicious actor can then send a request that the server incorrectly identifies as breaking server side invariants, which results in the server shutting down.

Mitigation

When possible, we recommend making sure to properly isolate your Valkey deployments so that only trusted users have access.

Credits

The problem was reported by NVIDIA Networking Security researchers:
Daniel Bransky github.com/dBransky
Eliya Cohen github.com/eliyacohen-hub

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2026-27623

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

Credits