# CVE-2026-39904: Gophish 0.12.1 Denial of Service via Office Document Upload

> Authenticated users can cause denial of service by uploading crafted Office documents that trigger memory exhaustion via zip bomb processing.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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:** 22 Jun 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-42jc-v69j-g38f, GO-2026-6212

## What is CVE-2026-39904?

CVE-2026-39904 is a high-severity denial of service vulnerability in gophish, published on 22 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Gophish through 0.12.1 contains a denial of service vulnerability that allows authenticated users with the User role to exhaust server memory by uploading a crafted Office document as an email template attachment. The ApplyTemplate() function in models/attachment.go processes Office documents as ZIP archives and calls ioutil.ReadAll() on each contained file entry without enforcing size restrictions on uncompressed content, allowing a zip bomb payload to expand to several gigabytes in memory and cause the process to be terminated by the operating system.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-39904?

3 open source packages ship an affected version, including github.com/gophish/gophish.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/gophish/gophish` | Go | All versions | None |
| `github.com/gophish/gophish` | Go | All versions to 0.12.1 | None |
| `github.com/gophish/gophish` | Go | All versions to 0.12.1 | None |

## How do I fix CVE-2026-39904?

Upgrade to a fixed version.

## Is CVE-2026-39904 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39904 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39904 and fix it if it is affected.

What it is: CVE-2026-39904 is a high-severity denial of service vulnerability in gophish, published on 22 Jun 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-2026-39904 exists.

Affected packages and fixed versions:
- github.com/gophish/gophish (Go): affected all versions; no fix listed
- github.com/gophish/gophish (Go): affected all versions up to 0.12.1; no fix listed
- github.com/gophish/gophish (Go): affected all versions up to 0.12.1; no fix listed

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-2026-39904/ (Markdown: https://insights.sbomify.com/CVE-2026-39904/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39904
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39904
- OSV: https://osv.dev/vulnerability/CVE-2026-39904

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39904/
Summaries are generated and may contain mistakes; the official description above is the record.