# CVE-2026-27623: Valkey denial of service via reachable assertion in RESP processing

Source: https://junglewise.ai/threats/cve-2026-27623-valkey-denial-of-service-via-reachable-assertion-in-resp  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-23. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-27623 · Severity: high · CVSS 7.5 · Published 2026-02-23

Valkey is a high-performance database used for storing and retrieving data quickly. A security flaw allows an attacker to crash the database server by sending a specifically formatted network request. This results in a service outage, making the database and any applications relying on it unavailable until it is restarted.

Technologies: [Lfprojects Valkey](https://junglewise.ai/threats/technologies/valkey), [Red Hat Enterprise Linux 10](https://junglewise.ai/threats/technologies/enterprise-linux-10), [Red Hat Enterprise Linux 9](https://junglewise.ai/threats/technologies/enterprise-linux-9). Vendors: [Lfprojects](https://junglewise.ai/threats/vendors/lfprojects), [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-27623 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-27623 being exploited in the wild.

**How severe is CVE-2026-27623?** High severity, with a CVSS score of 7.5, published 23 February 2026.

**Which products and versions are affected?** Red Hat Enterprise Linux 10 unaffected; Red Hat Enterprise Linux 9 unaffected.

**Is there a fix for CVE-2026-27623?** A patch was published on 2026-02-23: Fixed in version 9.0.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-27623 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-27623?** Check whether you run Lfprojects Valkey, Red Hat Enterprise Linux 10 or Red Hat Enterprise Linux 9 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A reachable assertion vulnerability (CWE-617) exists in Valkey versions 9.0.0 through 9.0.2. The root cause is a failure to properly reset the networking state after processing an empty RESP (Redis Serialization Protocol) request. An unauthenticated attacker with network access can exploit this by sending a subsequent malformed request that triggers a server-side invariant check, causing the process to abort. This results in a complete denial of service. The issue is resolved in Valkey version 9.0.3. Red Hat reports that their Enterprise Linux 9 and 10 implementations are currently unaffected.

## Affected products

- Valkey-io Valkey >= 9.0.0, < 9.0.3
- Red Hat Red Hat Enterprise Linux 9 unaffected
- Red Hat Red Hat Enterprise Linux 10 unaffected

## Timeline

- 2026-02-23: disclosed
- 2026-02-23: advisory
- 2026-02-23: patched: Fixed in version 9.0.3

## References

- [https://github.com/valkey-io/valkey/security/advisories/GHSA-93p9-5vc7-8wgr](https://github.com/valkey-io/valkey/security/advisories/GHSA-93p9-5vc7-8wgr)
- [https://access.redhat.com/security/cve/CVE-2026-27623](https://access.redhat.com/security/cve/CVE-2026-27623)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2442021](https://bugzilla.redhat.com/show_bug.cgi?id=2442021)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27623.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27623.json)

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