CVE-2026-27623 Valkey has Pre-Authentication DOS from malformed RESP request

What is CVE-2026-27623?

CVE-2026-27623 is a high-severity vulnerability in valkey-io valkey, published on 23 Feb 2026.

Official description

Valkey is a distributed key-value database. Starting in version 9.0.0 and prior to version 9.0.3, a malicious actor with network access to Valkey can cause the system to abort by triggering an assertion. 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. Version 9.0.3 fixes the issue. As an additional mitigation, properly isolate Valkey deployments so that only trusted users have access.

Weakness: CWE-617, CWE-20

Which versions are affected by CVE-2026-27623?

1 open source package ship an affected version, including valkey. It affects 1 product.

Products include Lfprojects Valkey.

How do I fix CVE-2026-27623?

Upgrade valkey to 9.0.3 or later.

Is CVE-2026-27623 being exploited?

There is no known exploitation of CVE-2026-27623 in the wild and no public exploit code.

Other vulnerabilities in valkey-io valkey

• CVE-2025-49844 Redis Lua Use-After-Free may lead to remote code execution Critical 10.0
• CVE-2025-67733 Valkey Affected by RESP Protocol Injection via Lua error_reply High 8.5
• CVE-2026-21863 Malformed Valkey Cluster bus message can lead to Remote DoS High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2026-27623, BIT-valkey-2026-27623, GHSA-93p9-5vc7-8wgr.