# CVE-2026-75004: Security feature bypass in Webmail

> Attackers can bypass disabled Sieve actions in Roundcube Webmail by crafting malicious rule names, requiring the managesieve plugin to be enabled.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-75004, GHSA-3247-mrpv-cpmj, UBUNTU-CVE-2026-75004

## What is CVE-2026-75004?

CVE-2026-75004 is a medium-severity vulnerability in Roundcube Webmail, published on 17 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, improper rule name quoting could lead to managesieve_disabled_actions setting bypass via a crafted rule name in a Sieve script. This issue only affects Roundcube instances using the managesieve plugin.

Weakness: CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2026-75004?

It affects 1 product.


Products: Roundcube Webmail.

## How do I fix CVE-2026-75004?

Upgrade to a fixed version.

## Is CVE-2026-75004 being exploited?

There is no known exploitation of CVE-2026-75004 in the wild and no public exploit code.

## Other vulnerabilities in Roundcube Webmail

- [CVE-2024-42009](https://insights.sbomify.com/CVE-2024-42009/): RoundCube Webmail Cross-Site Scripting (critical 9.3, exploited in the wild)
- [CVE-2025-68461](https://insights.sbomify.com/CVE-2025-68461/): RoundCube Webmail Cross-site Scripting (high 7.2, exploited in the wild)
- [CVE-2008-5619](https://insights.sbomify.com/CVE-2008-5619/): PHPMailer susceptible to arbitrary code execution (critical 10.0)
- [CVE-2024-37385](https://insights.sbomify.com/CVE-2024-37385/): Command injection in n/a (critical 9.8)
- [CVE-2024-42008](https://insights.sbomify.com/CVE-2024-42008/): Cross-site scripting in n/a (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75004 and fix it if it is affected.

What it is: CVE-2026-75004 is a medium-severity vulnerability in Roundcube Webmail, published on 17 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-75004 in the wild and no public exploit code.

Affected product: Roundcube Webmail. 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-2026-75004/ (Markdown: https://insights.sbomify.com/CVE-2026-75004/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75004
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75004
- OSV: https://osv.dev/vulnerability/CVE-2026-75004

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-75004/
Summaries are generated and may contain mistakes; the official description above is the record.