# CVE-2026-29136: CA Notification HTML Injection

> Attackers can inject HTML into CA certificate notification emails, potentially executing scripts or bypassing security controls in SEPPmail Secure Email Gateway.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 2 Apr 2026
- **Updated:** 2 Apr 2026
- **Also known as:** GHSA-9cfw-4wfr-8gwf

## What is CVE-2026-29136?

CVE-2026-29136 is a medium-severity cross-site scripting vulnerability in SEPPmail Secure Email Gateway, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

SEPPmail Secure Email Gateway before version 15.0.3 allows an attacker to inject HTML into notification emails about new CA certificates.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-29136?

It affects 1 product.


Products: Seppmail Secure Email Gateway.

## How do I fix CVE-2026-29136?

No fix has been published for CVE-2026-29136 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-29136 being exploited?

There is no known exploitation of CVE-2026-29136 in the wild and no public exploit code.

## Other vulnerabilities in SEPPmail Secure Email Gateway

- [CVE-2026-29139](https://insights.sbomify.com/CVE-2026-29139/): GINA State Confusion Account Takeover (high 7.8)
- [CVE-2026-29143](https://insights.sbomify.com/CVE-2026-29143/): S/MIME Decryption Impersonation (high 7.8)
- [CVE-2026-29144](https://insights.sbomify.com/CVE-2026-29144/): Unicode Subject Tags (high 7.8)
- [CVE-2026-29140](https://insights.sbomify.com/CVE-2026-29140/): S/MIME Signature Additional Certificate (high 7.7)
- [CVE-2026-29141](https://insights.sbomify.com/CVE-2026-29141/): Bounded Subject Tag Sanitization (high 7.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-29136 and fix it if it is affected.

What it is: CVE-2026-29136 is a medium-severity cross-site scripting vulnerability in SEPPmail Secure Email Gateway, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-29136 in the wild and no public exploit code.

Affected product: SEPPmail Secure Email Gateway. 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-2026-29136/ (Markdown: https://insights.sbomify.com/CVE-2026-29136/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-29136
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-29136
- OSV: https://osv.dev/vulnerability/CVE-2026-29136

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-29136/
Summaries are generated and may contain mistakes; the official description above is the record.