# CVE-2026-1323: Insecure Deserialization in extension "Mailqueue" (mailqueue)

> An attacker with write access to the mail spool directory can execute arbitrary code via insecure deserialization in the TYPO3 Mailqueue extension.

- **Severity:** Medium 5.2 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Mar 2026
- **Updated:** 17 Mar 2026
- **Also known as:** GHSA-2pm6-9fhx-vvg3

## What is CVE-2026-1323?

CVE-2026-1323 is a medium-severity unsafe deserialization vulnerability in TYPO3 Extension "Mailqueue", published on 17 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The extension fails to properly define allowed classes used when deserializing transport failure metadata. An attacker may exploit this to execute untrusted serialized code. Note that an active exploit requires write access to the directory configured at $GLOBALS['TYPO3_CONF_VARS']['MAIL']['transport_spool_filepath'].

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-1323?

4 open source packages ship an affected version, including cpsit/typo3-mailqueue. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `cpsit/typo3-mailqueue` | Packagist | All versions | 0.4.5 |
| `cpsit/typo3-mailqueue` | Packagist | All versions | 0.4.5 |
| `cpsit/typo3-mailqueue` | Packagist | From 0.5.0 | 0.5.2 |
| `cpsit/typo3-mailqueue` | Packagist | From 0.5.0 | 0.5.2 |

Products: Cps-It Mailqueue.

## How do I fix CVE-2026-1323?

Upgrade cpsit/typo3-mailqueue to a fixed version for your release line: 0.4.5 or 0.5.2.

## Is CVE-2026-1323 being exploited?

There is no known exploitation of CVE-2026-1323 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-1323 and fix it if it is affected.

What it is: CVE-2026-1323 is a medium-severity unsafe deserialization vulnerability in TYPO3 Extension "Mailqueue", published on 17 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-1323 in the wild and no public exploit code.

Affected packages and fixed versions:
- cpsit/typo3-mailqueue (Packagist): affected all versions; fixed in 0.4.5
- cpsit/typo3-mailqueue (Packagist): affected all versions; fixed in 0.4.5
- cpsit/typo3-mailqueue (Packagist): affected from 0.5.0; fixed in 0.5.2
- cpsit/typo3-mailqueue (Packagist): affected from 0.5.0; fixed in 0.5.2

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-2026-1323/ (Markdown: https://insights.sbomify.com/CVE-2026-1323/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-1323
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-1323
- OSV: https://osv.dev/vulnerability/CVE-2026-1323

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-1323/
Summaries are generated and may contain mistakes; the official description above is the record.