# CVE-2021-3470: Memory corruption in redis

> Heap overflow in Redis when using non-standard allocators allows out-of-bounds writes, potentially leading to code execution or crashes.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Mar 2021
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-3470, AZL-6852, CLEANSTART-2026-BW73910, DEBIAN-CVE-2021-3470, GHSA-mqmr-8cxh-pqf6, OESA-2021-1172, UBUNTU-CVE-2021-3470

## What is CVE-2021-3470?

CVE-2021-3470 is a medium-severity memory corruption vulnerability in redis, published on 31 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A heap overflow issue was found in Redis in versions before 5.0.10, before 6.0.9 and before 6.2.0 when using a heap allocator other than jemalloc or glibc's malloc, leading to potential out of bound write or process crash. Effectively this flaw does not affect the vast majority of users, who use jemalloc or glibc malloc.

Weakness: CWE-787 (Out-of-bounds Write), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-3470?

It affects 1 product.


Products: Redislabs Redis.

## How do I fix CVE-2021-3470?

Upgrade to a fixed version.

## Is CVE-2021-3470 being exploited?

There is no known exploitation of CVE-2021-3470 in the wild and no public exploit code.

## Other vulnerabilities in redis

- [CVE-2017-15047](https://insights.sbomify.com/CVE-2017-15047/): Denial of service in n/a (critical 9.8)
- [CVE-2018-12326](https://insights.sbomify.com/CVE-2018-12326/): Memory corruption in n/a (high 8.4)
- [CVE-2020-21468](https://insights.sbomify.com/CVE-2020-21468/): Denial of service in n/a (high 7.5)
- [CVE-2018-12453](https://insights.sbomify.com/CVE-2018-12453/): Denial of service in n/a (high 7.5)
- [CVE-2016-10517](https://insights.sbomify.com/CVE-2016-10517/): Other in n/a (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3470 and fix it if it is affected.

What it is: CVE-2021-3470 is a medium-severity memory corruption vulnerability in redis, published on 31 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-3470 in the wild and no public exploit code.

Affected product: redis. 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-2021-3470/ (Markdown: https://insights.sbomify.com/CVE-2021-3470/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3470
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3470
- OSV: https://osv.dev/vulnerability/CVE-2021-3470

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3470/
Summaries are generated and may contain mistakes; the official description above is the record.