# CVE-2021-32628: Vulnerability in handling large ziplists

> An integer overflow in Redis ziplist handling allows remote code execution if default configuration limits are increased, requiring an upgrade or ACL restrictions.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/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:** Yes
- **Published:** 4 Oct 2021
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-32628, AZL-6846, BIT-keydb-2021-32628, BIT-redis-2021-32628, BIT-valkey-2021-32628, CLEANSTART-2026-NQ76206, DEBIAN-CVE-2021-32628, GHSA-vw22-qm3h-49pr, UBUNTU-CVE-2021-32628

## What is CVE-2021-32628?

CVE-2021-32628 is a high-severity vulnerability in Debian Debian Linux, published on 4 Oct 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Redis is an open source, in-memory database that persists on disk. An integer overflow bug in the ziplist data structure used by all versions of Redis can be exploited to corrupt the heap and potentially result with remote code execution. The vulnerability involves modifying the default ziplist configuration parameters (hash-max-ziplist-entries, hash-max-ziplist-value, zset-max-ziplist-entries or zset-max-ziplist-value) to a very large value, and then constructing specially crafted commands to create very large ziplists. The problem is fixed in Redis versions 6.2.6, 6.0.16, 5.0.14. An additional workaround to mitigate the problem without patching the redis-server executable is to prevent users from modifying the above configuration parameters. This can be done using ACL to restrict unprivileged users from using the CONFIG SET command.

Weakness: CWE-680 (Integer Overflow to Buffer Overflow), CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2021-32628?

3 open source packages ship an affected version, including keydb, redis and valkey. It affects 6 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `keydb` | Bitnami | From 5.0.0 | 5.0.14, 6.0.16, 6.2.6 |
| `redis` | Bitnami | From 5.0.0 | 5.0.14, 6.0.16, 6.2.6 |
| `valkey` | Bitnami | From 5.0.0 | 5.0.14, 6.0.16, 6.2.6 |

Products: Debian Debian Linux, Fedoraproject Fedora, Netapp Management Services for Element Software, Netapp Management Services for Netapp Hci, Oracle Communications Operations Monitor, Redis Redis.

## How do I fix CVE-2021-32628?

Upgrade keydb to a fixed version for your release line: 5.0.14, 6.0.16 or 6.2.6.

## Is CVE-2021-32628 being exploited?

There is no known exploitation of CVE-2021-32628 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32628 and fix it if it is affected.

What it is: CVE-2021-32628 is a high-severity vulnerability in Debian Debian Linux, published on 4 Oct 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-32628 in the wild and no public exploit code.

Affected packages and fixed versions:
- keydb (Bitnami): affected from 5.0.0; fixed in 5.0.14, 6.0.16, 6.2.6
- redis (Bitnami): affected from 5.0.0; fixed in 5.0.14, 6.0.16, 6.2.6
- valkey (Bitnami): affected from 5.0.0; fixed in 5.0.14, 6.0.16, 6.2.6

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-2021-32628/ (Markdown: https://insights.sbomify.com/CVE-2021-32628/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32628
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32628
- OSV: https://osv.dev/vulnerability/CVE-2021-32628

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32628/
Summaries are generated and may contain mistakes; the official description above is the record.