# CVE-2021-20314: Memory corruption in libspf2

> A stack buffer overflow in libspf2 allows attackers to cause denial of service or execute code via crafted SPF messages.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Aug 2021
- **Updated:** 13 Feb 2025
- **Also known as:** ALPINE-CVE-2021-20314, DEBIAN-CVE-2021-20314, DLA-2739-1, DSA-4955-1, GHSA-7mf9-xf4j-h63m, MGASA-2021-0414, MGASA-2021-0454, UBUNTU-CVE-2021-20314, openSUSE-SU-2021:1187-1, openSUSE-SU-2024:10995-1

## What is CVE-2021-20314?

CVE-2021-20314 is a critical memory corruption vulnerability in Fedoraproject Fedora, published on 12 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Stack buffer overflow in libspf2 versions below 1.2.11 when processing certain SPF macros can lead to Denial of service and potentially code execution via malicious crafted SPF explanation messages.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-20314?

It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libspf2` | SUSE:Package Hub 15 SP1 | All versions | 1.2.10-bp153.5.1 |
| `libspf2` | SUSE:Package Hub 15 SP2 | All versions | 1.2.10-bp153.5.1 |
| `libspf2` | SUSE:Package Hub 15 SP3 | All versions | 1.2.10-bp153.5.1 |
| `libspf2` | openSUSE:Leap 15.2 | All versions | 1.2.10-bp153.5.1 |
| `libspf2` | openSUSE:Leap 15.3 | All versions | 1.2.10-bp153.5.1 |
| `libspf2` | openSUSE:Tumbleweed | All versions | 0.01-5.3 |

Products: Fedoraproject Fedora, Libspf2 Libspf2, Redhat Enterprise Linux.

## How do I fix CVE-2021-20314?

Upgrade to a fixed version.

## Is CVE-2021-20314 being exploited?

There is no known exploitation of CVE-2021-20314 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20314 and fix it if it is affected.

What it is: CVE-2021-20314 is a critical memory corruption vulnerability in Fedoraproject Fedora, published on 12 Aug 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-2021-20314 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2021-20314/ (Markdown: https://insights.sbomify.com/CVE-2021-20314/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20314
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20314
- OSV: https://osv.dev/vulnerability/CVE-2021-20314

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20314/
Summaries are generated and may contain mistakes; the official description above is the record.