# CVE-2026-21864: Remote DoS from malformed RESTORE command

> A remote attacker can crash the Valkey database server by sending a malformed RESTORE command to the Bloom module.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Feb 2026
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-mc2g-h759-3qw2

## What is CVE-2026-21864?

CVE-2026-21864 is a medium-severity denial of service vulnerability in valkey-io valkey-bloom, published on 24 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Valkey-Bloom is a Rust based Valkey module which brings a Bloom Filter (Module) data type into the Valkey distributed key-value database. Prior to commit a68614b6e3845777d383b3a513cedcc08b3b7ccd, a specially crafted `RESTORE` command can cause Valkey to hit an assertion, causes the server to shutdown. Valkey modules are required to handle errors in RDB parsing by using `VALKEYMODULE_OPTIONS_HANDLE_IO_ERRORS` flag. If this flag is not set, errors encountered during parsing result in a system assertion which shuts down the system. Even though the Valkey-bloom module correctly handled the parsing, it did not originally set the flag. Commit a68614b6e3845777d383b3a513cedcc08b3b7ccd contains a patch. One may mitigate this defect by disabling the `RESTORE` command if it is unused by one's application.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-21864?

It affects 1 product.


Products: Lfprojects Valkey-Bloom.

## How do I fix CVE-2026-21864?

No fix has been published for CVE-2026-21864 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-21864 being exploited?

There is no known exploitation of CVE-2026-21864 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21864 and fix it if it is affected.

What it is: CVE-2026-21864 is a medium-severity denial of service vulnerability in valkey-io valkey-bloom, published on 24 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-21864 in the wild and no public exploit code.

Affected product: valkey-io valkey-bloom. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-21864/ (Markdown: https://insights.sbomify.com/CVE-2026-21864/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21864
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21864
- OSV: https://osv.dev/vulnerability/CVE-2026-21864

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-21864/
Summaries are generated and may contain mistakes; the official description above is the record.