# CVE-2026-82631: valkey-io valkey Blocked-on-keys blocked.c handleClientsBlockedOnKey use after free

> Remote attackers can exploit a use-after-free flaw in Valkey's blocked-on-keys subsystem, potentially leading to code execution or service disruption.

- **Severity:** Low 2.1 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** AZL-98439, BELL-CVE-2026-82631, DEBIAN-CVE-2026-82631, ECHO-fc1f-17d4-9ed1, GHSA-vxq6-76gw-j6q5, UBUNTU-CVE-2026-82631

## What is CVE-2026-82631?

CVE-2026-82631 is a low-severity use after free vulnerability in valkey-io valkey, published on 31 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A security flaw has been discovered in valkey-io valkey 9.1.0. The affected element is the function handleClientsBlockedOnKey of the file src/blocked.c of the component Blocked-on-keys Subsystem. The manipulation results in use after free. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is described as difficult. The exploit has been released to the public and may be used for attacks. The patch is identified as b2fb0e13f5b4c8c2fb63dcfc2c37a067a0d6d20b. Applying a patch is advised to resolve this issue.

Weakness: CWE-416 (Use After Free), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-82631?


## How do I fix CVE-2026-82631?

Apply the vendor's patch.

## Is CVE-2026-82631 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82631 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82631 and fix it if it is affected.

What it is: CVE-2026-82631 is a low-severity use after free vulnerability in valkey-io valkey, published on 31 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82631 exists.

Affected product: valkey-io valkey. 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-2026-82631/ (Markdown: https://insights.sbomify.com/CVE-2026-82631/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82631
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82631
- OSV: https://osv.dev/vulnerability/CVE-2026-82631

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82631/
Summaries are generated and may contain mistakes; the official description above is the record.