CVE-2026-27064 WordPress Mailster plugin <= 4.1.17 - Arbitrary File Upload vulnerability
Critical 9.1
Published
Updated
Check this codebase for CVE-2026-27064 and fix it if it is affected.
What it is: CVE-2026-27064 is a critical vulnerability in EverPress Mailster, published on 23 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-27064 in the wild and no public exploit code.
Affected product: EverPress Mailster. 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-2026-27064/ (Markdown: https://insights.sbomify.com/CVE-2026-27064/index.md)
An attacker with editor privileges can upload arbitrary files to the Mailster WordPress plugin, potentially leading to remote code execution.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-27064?
CVE-2026-27064 is a critical vulnerability in EverPress Mailster, published on 23 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Editor Arbitrary File Upload in Mailster <= 4.1.17 versions.
Weakness: CWE-434
Which versions are affected by CVE-2026-27064?
How do I fix CVE-2026-27064?
No fix has been published for CVE-2026-27064 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-27064 being exploited?
There is no known exploitation of CVE-2026-27064 in the wild and no public exploit code.
Sources
Also known as GHSA-qwf2-rfq8-mpjg.