# CVE-2026-55809: Flag attendance field - Critical - PHP object injection - SA-CONTRIB-2026-049

> An attacker can exploit PHP object injection in the Drupal Flag attendance field plugin to potentially execute arbitrary code.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 10 Jul 2026
- **Updated:** 13 Jul 2026
- **Also known as:** DRUPAL-CONTRIB-2026-049, GHSA-66vp-2cwc-4pv3

## What is CVE-2026-55809?

CVE-2026-55809 is a high-severity unsafe deserialization vulnerability in Drupal Flag attendance field, published on 10 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerability in Drupal Flag attendance field allows Object Injection. This issue affects Flag attendance field versions: from 0.0.0 to 1.2.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes)

## Which versions are affected by CVE-2026-55809?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `drupal/flag_attendance_field` | Packagist:https://packages.drupal.org/8 | All versions | 1.2.0 |

Products: Flag Attendance Field Project Flag Attendance Field.

## How do I fix CVE-2026-55809?

Upgrade to a fixed version.

## Is CVE-2026-55809 being exploited?

There is no known exploitation of CVE-2026-55809 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55809 and fix it if it is affected.

What it is: CVE-2026-55809 is a high-severity unsafe deserialization vulnerability in Drupal Flag attendance field, published on 10 Jul 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-2026-55809 in the wild and no public exploit code.

Affected product: Drupal Flag attendance field. 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-2026-55809/ (Markdown: https://insights.sbomify.com/CVE-2026-55809/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55809
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55809
- OSV: https://osv.dev/vulnerability/CVE-2026-55809

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55809/
Summaries are generated and may contain mistakes; the official description above is the record.