# CVE-2021-32761: Integer overflow issues with *BIT commands on 32-bit systems

> Integer overflow in Redis BIT commands on 32-bit systems allows heap corruption, information disclosure, or remote code execution if proto-max-bulk-len is increased.

- **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:** 21 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-32761, AZL-6850, CLEANSTART-2026-GZ27541, DEBIAN-CVE-2021-32761, DLA-2717-1, DLA-2717-2, GHSA-8wxq-j7rp-g8wj, UBUNTU-CVE-2021-32761

## What is CVE-2021-32761?

CVE-2021-32761 is a high-severity vulnerability in Debian Debian Linux, published on 21 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Redis is an in-memory database that persists on disk. A vulnerability involving out-of-bounds read and integer overflow to buffer overflow exists starting with version 2.2 and prior to versions 5.0.13, 6.0.15, and 6.2.5. On 32-bit systems, Redis `*BIT*` command are vulnerable to integer overflow that can potentially be exploited to corrupt the heap, leak arbitrary heap contents or trigger remote code execution. The vulnerability involves changing the default `proto-max-bulk-len` configuration parameter to a very large value and constructing specially crafted commands bit commands. This problem only affects Redis on 32-bit platforms, or compiled as a 32-bit binary. Redis versions 5.0.`3m 6.0.15, and 6.2.5 contain patches for this issue. An additional workaround to mitigate the problem without patching the `redis-server` executable is to prevent users from modifying the `proto-max-bulk-len` configuration parameter. This can be done using ACL to restrict unprivileged users from using the CONFIG SET command.

Weakness: CWE-190 (Integer Overflow or Wraparound), CWE-680 (Integer Overflow to Buffer Overflow), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2021-32761?

It affects 3 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Redislabs Redis.

## How do I fix CVE-2021-32761?

Apply the vendor's patch.

## Is CVE-2021-32761 being exploited?

There is no known exploitation of CVE-2021-32761 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-2021-32761 and fix it if it is affected.

What it is: CVE-2021-32761 is a high-severity vulnerability in Debian Debian Linux, published on 21 Jul 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-2021-32761 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2021-32761/ (Markdown: https://insights.sbomify.com/CVE-2021-32761/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32761
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32761
- OSV: https://osv.dev/vulnerability/CVE-2021-32761

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32761/
Summaries are generated and may contain mistakes; the official description above is the record.