# CVE-2021-32762: Integer overflow that can lead to heap overflow in redis-cli, redis-sentinel on some platforms

> Integer overflow in hiredis library used by redis-cli and redis-sentinel can lead to heap overflow and potential code execution on systems without allocator overflow checks.

- **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-2021-32762, AZL-61842, AZL-6851, BIT-keydb-2021-32762, BIT-redis-2021-32762, BIT-valkey-2021-32762, CLEANSTART-2026-EF94463, DEBIAN-CVE-2021-32762, GHSA-833w-8v3m-8wwr, UBUNTU-CVE-2021-32762

## What is CVE-2021-32762?

CVE-2021-32762 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. The redis-cli command line tool and redis-sentinel service may be vulnerable to integer overflow when parsing specially crafted large multi-bulk network replies. This is a result of a vulnerability in the underlying hiredis library which does not perform an overflow check before calling the calloc() heap allocation function. This issue only impacts systems with heap allocators that do not perform their own overflow checks. Most modern systems do and are therefore not likely to be affected. Furthermore, by default redis-sentinel uses the jemalloc allocator which is also not vulnerable. The problem is fixed in Redis versions 6.2.6, 6.0.16 and 5.0.14.

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

## Which versions are affected by CVE-2021-32762?

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-2021-32762?

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

## Is CVE-2021-32762 being exploited?

There is no known exploitation of CVE-2021-32762 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-2021-32762 and fix it if it is affected.

What it is: CVE-2021-32762 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-2021-32762 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-2021-32762/ (Markdown: https://insights.sbomify.com/CVE-2021-32762/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32762
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32762
- OSV: https://osv.dev/vulnerability/CVE-2021-32762

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32762/
Summaries are generated and may contain mistakes; the official description above is the record.