# CVE-2026-16267: Newsletters < 4.16 - Unauthenticated PHP Object Injection via Date Form Field

> Unauthenticated attackers can inject arbitrary PHP objects via the date form field in the Newsletters plugin, potentially leading to code execution.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Aug 2026
- **Updated:** 11 Aug 2026
- **Also known as:** GHSA-jxc3-pfg8-hv86

## What is CVE-2026-16267?

CVE-2026-16267 is a high-severity unsafe deserialization vulnerability in Unknown Newsletters, published on 8 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Newsletters WordPress plugin before 4.16 does not restrict the classes allowed when unserialising a value taken from a public form submission, allowing unauthenticated attackers to inject arbitrary PHP objects.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-16267?


## How do I fix CVE-2026-16267?

No fix has been published for CVE-2026-16267 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-16267 being exploited?

There is no known exploitation of CVE-2026-16267 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16267 and fix it if it is affected.

What it is: CVE-2026-16267 is a high-severity unsafe deserialization vulnerability in Unknown Newsletters, published on 8 Aug 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-2026-16267 in the wild and no public exploit code.

Affected product: Unknown Newsletters. 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-2026-16267/ (Markdown: https://insights.sbomify.com/CVE-2026-16267/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16267
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16267
- OSV: https://osv.dev/vulnerability/CVE-2026-16267

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16267/
Summaries are generated and may contain mistakes; the official description above is the record.