# CVE-2026-45067: Symfony: Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address

> Attackers can inject SMTP commands or email headers via CRLF in Symfony Mailer addresses, potentially executing code or modifying messages.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Jul 2026
- **Updated:** 14 Jul 2026
- **Also known as:** CLSA-2026-1782781183, DEBIAN-CVE-2026-45067, GHSA-qpmx-3rfj-7rhv, UBUNTU-CVE-2026-45067

## What is CVE-2026-45067?

CVE-2026-45067 is a medium-severity command injection vulnerability in symfony, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

### Description

`Symfony\Component\Mime\Address` is the value-object every Symfony Mailer address (to/cc/bcc/from/reply-to) flows through; its constructor is documented as validating the address and throwing on invalid input, so developers treat it as a security boundary.

The constructor accepts email addresses whose local-part (the part before `@`) is an RFC-5322 *quoted string* containing raw `\r\n` bytes — e.g. `"x\r\nBcc: attacker@evil"@example.com`. The stored address is later emitted verbatim into (1) the rendered message headers and (2) `SmtpTransport`'s `MAIL FROM:<...>` / `RCPT TO:<...>` protocol lines, turning the embedded CRLF into a new mail header and/or a new SMTP command.

### Resolution

The `Address` constructor now rejects addresses containing line breaks.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/dc2dbd29211eb4ddc451373fa1374fb926e94604) for branch 5.4.

### Credits

We would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences)

## Which versions are affected by CVE-2026-45067?

16 open source packages ship an affected version, including symfony/mime and symfony/symfony.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `symfony/mime` | Packagist | All versions | 5.4.52 |
| `symfony/mime` | Packagist | All versions | 5.4.52 |
| `symfony/mime` | Packagist | From 6.0.0 | 6.4.40 |
| `symfony/mime` | Packagist | From 6.0.0 | 6.4.40 |
| `symfony/mime` | Packagist | From 7.0.0 | 7.4.12 |
| `symfony/mime` | Packagist | From 7.0.0 | 7.4.12 |
| `symfony/mime` | Packagist | From 8.0.0 | 8.0.12 |
| `symfony/mime` | Packagist | From 8.0.0 | 8.0.12 |
| `symfony/symfony` | Packagist | All versions | 5.4.52 |
| `symfony/symfony` | Packagist | All versions | 5.4.52 |
| `symfony/symfony` | Packagist | From 6.0.0 | 6.4.40 |
| `symfony/symfony` | Packagist | From 6.0.0 | 6.4.40 |
| `symfony/symfony` | Packagist | From 7.0.0 | 7.4.12 |
| `symfony/symfony` | Packagist | From 7.0.0 | 7.4.12 |
| `symfony/symfony` | Packagist | From 8.0.0 | 8.0.12 |
| `symfony/symfony` | Packagist | From 8.0.0 | 8.0.12 |

## How do I fix CVE-2026-45067?

Upgrade symfony/mime to a fixed version for your release line: 5.4.52, 6.4.40, 7.4.12 or 8.0.12.

## Is CVE-2026-45067 being exploited?

There is no known exploitation of CVE-2026-45067 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-45067 - Draft (github_poc): https://github.com/HORKimhab/CVE-2026-45067

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45067 and fix it if it is affected.

What it is: CVE-2026-45067 is a medium-severity command injection vulnerability in symfony, published on 14 Jul 2026. 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-2026-45067 in the wild and no public exploit code.

Affected packages and fixed versions:
- symfony/mime (Packagist): affected all versions; fixed in 5.4.52
- symfony/mime (Packagist): affected all versions; fixed in 5.4.52
- symfony/mime (Packagist): affected from 6.0.0; fixed in 6.4.40
- symfony/mime (Packagist): affected from 6.0.0; fixed in 6.4.40
- symfony/mime (Packagist): affected from 7.0.0; fixed in 7.4.12
- symfony/mime (Packagist): affected from 7.0.0; fixed in 7.4.12
- symfony/mime (Packagist): affected from 8.0.0; fixed in 8.0.12
- symfony/mime (Packagist): affected from 8.0.0; fixed in 8.0.12
- symfony/symfony (Packagist): affected all versions; fixed in 5.4.52
- symfony/symfony (Packagist): affected all versions; fixed in 5.4.52
- symfony/symfony (Packagist): affected from 6.0.0; fixed in 6.4.40
- symfony/symfony (Packagist): affected from 6.0.0; fixed in 6.4.40

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-2026-45067/ (Markdown: https://insights.sbomify.com/CVE-2026-45067/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45067
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45067
- OSV: https://osv.dev/vulnerability/CVE-2026-45067

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45067/
Summaries are generated and may contain mistakes; the official description above is the record.