# CVE-2023-51765: Security feature bypass in n/a

> Remote attackers can bypass SPF protection by injecting emails with spoofed sender addresses due to SMTP smuggling in specific sendmail configurations.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Dec 2023
- **Updated:** 2 Aug 2024
- **Also known as:** AZL-32295, DEBIAN-CVE-2023-51765, DLA-3829-1, GHSA-5rcq-25vc-g8qr, MGASA-2024-0270, SUSE-SU-2024:0742-1, SUSE-SU-2024:0743-1, UBUNTU-CVE-2023-51765, openSUSE-SU-2024:13658-1

## What is CVE-2023-51765?

CVE-2023-51765 is a medium-severity vulnerability in Freebsd Freebsd, published on 24 Dec 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

sendmail through 8.17.2 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports <LF>.<CR><LF> but some other popular e-mail servers do not. This is resolved in 8.18 and later versions with 'o' in srv_features.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2023-51765?

It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `sendmail` | SUSE:Linux Enterprise Module for Basesystem 15 SP5 | All versions | 8.15.2-150000.8.12.1 |
| `sendmail` | SUSE:Linux Enterprise Module for Legacy 12 | All versions | 8.14.9-4.9.1 |
| `sendmail` | SUSE:Linux Enterprise Module for Package Hub 15 SP5 | All versions | 8.15.2-150000.8.12.1 |
| `sendmail` | openSUSE:Leap 15.5 | All versions | 8.15.2-150000.8.12.1 |

Products: Freebsd Freebsd, Redhat Enterprise Linux, Sendmail Sendmail.

## How do I fix CVE-2023-51765?

Upgrade to a fixed version.

## Is CVE-2023-51765 being exploited?

There is no known exploitation of CVE-2023-51765 in the wild and no public exploit code.

## Other vulnerabilities in Freebsd Freebsd

- [CVE-2018-17160](https://insights.sbomify.com/CVE-2018-17160/): Memory corruption in FreeBSD (critical 10.0)
- [CVE-2014-3954](https://insights.sbomify.com/CVE-2014-3954/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-4304](https://insights.sbomify.com/CVE-2006-4304/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-0226](https://insights.sbomify.com/CVE-2006-0226/): Integer overflow in n/a (critical 10.0)
- [CVE-2004-0002](https://insights.sbomify.com/CVE-2004-0002/): Denial of service in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-51765 and fix it if it is affected.

What it is: CVE-2023-51765 is a medium-severity vulnerability in Freebsd Freebsd, published on 24 Dec 2023. 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-2023-51765 in the wild and no public exploit code.

Affected product: Freebsd Freebsd. 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-2023-51765/ (Markdown: https://insights.sbomify.com/CVE-2023-51765/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-51765
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-51765
- OSV: https://osv.dev/vulnerability/CVE-2023-51765

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-51765/
Summaries are generated and may contain mistakes; the official description above is the record.