# CVE-2026-3967: Alfresco Activiti Process Variable Serialization System SerializableType.java createObjectInputStream deserialization

> Remote attackers can execute arbitrary code via unsafe deserialization in the Activiti process variable serialization system.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-7wmq-q36p-g2wg

## What is CVE-2026-3967?

CVE-2026-3967 is a medium-severity unsafe deserialization vulnerability in Alfresco Activiti, published on 12 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw has been found in Alfresco Activiti up to 7.19/8.8.0. Affected by this issue is the function deserialize/createObjectInputStream of the file activiti-core/activiti-engine/src/main/java/org/activiti/engine/impl/variable/SerializableType.java of the component Process Variable Serialization System. This manipulation causes deserialization. Remote exploitation of the attack is possible. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-502 (Deserialization of Untrusted Data), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-3967?


## How do I fix CVE-2026-3967?

No fix has been published for CVE-2026-3967 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-3967 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3967 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3967 and fix it if it is affected.

What it is: CVE-2026-3967 is a medium-severity unsafe deserialization vulnerability in Alfresco Activiti, published on 12 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3967 exists.

Affected product: Alfresco Activiti. 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-2026-3967/ (Markdown: https://insights.sbomify.com/CVE-2026-3967/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3967
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3967
- OSV: https://osv.dev/vulnerability/CVE-2026-3967

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-3967/
Summaries are generated and may contain mistakes; the official description above is the record.