# CVE-2021-31988: Other in AXIS OS

> Attackers can inject CRLF characters into SMTP test emails to add arbitrary headers, potentially manipulating email content or metadata.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:** A user has to click or open something
- **Fix available:** No
- **Published:** 5 Oct 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-9whv-vchq-g94v

## What is CVE-2021-31988?

CVE-2021-31988 is a high-severity vulnerability in AXIS OS, published on 5 Oct 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A user controlled parameter related to SMTP test functionality is not correctly validated making it possible to add the Carriage Return and Line Feed (CRLF) control characters and include arbitrary SMTP headers in the generated test email.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-1286 (Improper Validation of Syntactic Correctness of Input)

## Which versions are affected by CVE-2021-31988?

It affects 4 products.


Products: Axis Axis Os, Axis Axis Os 2016, Axis Axis Os 2018, Axis Axis Os 2020.

## How do I fix CVE-2021-31988?

No fix has been published for CVE-2021-31988 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-31988 being exploited?

There is no known exploitation of CVE-2021-31988 in the wild and no public exploit code.

## Other vulnerabilities in AXIS OS

- [CVE-2025-0324](https://insights.sbomify.com/CVE-2025-0324/): Privilege escalation in AXIS OS (critical 9.4)
- [CVE-2023-21413](https://insights.sbomify.com/CVE-2023-21413/): Remote code execution vulnerability during the installation of ACAP applications on the Axis device (critical 9.1)
- [CVE-2025-0358](https://insights.sbomify.com/CVE-2025-0358/): Privilege escalation in AXIS OS (high 8.8)
- [CVE-2025-0359](https://insights.sbomify.com/CVE-2025-0359/): Missing authorization in AXIS OS (high 8.5)
- [CVE-2025-0360](https://insights.sbomify.com/CVE-2025-0360/): Privilege escalation in AXIS OS (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31988 and fix it if it is affected.

What it is: CVE-2021-31988 is a high-severity vulnerability in AXIS OS, published on 5 Oct 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-31988 in the wild and no public exploit code.

Affected product: AXIS OS. 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-2021-31988/ (Markdown: https://insights.sbomify.com/CVE-2021-31988/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31988
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31988
- OSV: https://osv.dev/vulnerability/CVE-2021-31988

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31988/
Summaries are generated and may contain mistakes; the official description above is the record.