# CVE-2026-28809: XXE in esaml SAML library allows local file read and potential SSRF


- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 23 Mar 2026
- **Updated:** 24 Jul 2026
- **Also known as:** EEF-CVE-2026-28809, GHSA-4g2h-vm7x-747c

## What is CVE-2026-28809?

CVE-2026-28809 is a medium-severity vulnerability in Jump-App esaml, published on 23 Mar 2026. 

### Official description

XML External Entity (XXE) vulnerability in esaml (and its forks) allows an attacker to cause the system to read local files and incorporate their contents into processed SAML documents, and potentially perform SSRF via crafted SAML messages.

esaml parses attacker-controlled SAML messages using xmerl_scan:string/2 before signature verification without disabling XML entity expansion. On Erlang/OTP versions before 27, Xmerl allows entities by default, enabling pre-signature XXE attacks. An attacker can cause the host to read local files (e.g., Kubernetes-mounted secrets) into the SAML document. If the attacker is not a trusted SAML SP, signature verification will fail and the document is discarded, but file contents may still be exposed through logs or error messages.

This issue affects all versions of esaml, including forks by arekinath, handnot2, and dropbox. Users running on Erlang/OTP 27 or later are not affected due to Xmerl defaulting to entities disabled.

Weakness: CWE-611 (Improper Restriction of XML External Entity Reference)

## Which versions are affected by CVE-2026-28809?

3 open source packages ship an affected version, including esaml. It affects 4 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `esaml` | Hex | All versions | None |
| `esaml` | Hex | All versions to 4.6.0 | None |
| `esaml` | Hex | All versions to 4.6.0 | None |

Products: Arekinath Esaml, Dropbox Esaml, Handnot2 Esaml, Jump-App Esaml.

## How do I fix CVE-2026-28809?

No fix has been published for CVE-2026-28809 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-28809 being exploited?

There is no known exploitation of CVE-2026-28809 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28809 and fix it if it is affected.

What it is: CVE-2026-28809 is a medium-severity vulnerability in Jump-App esaml, published on 23 Mar 2026. 
Exploitation: There is no known exploitation of CVE-2026-28809 in the wild and no public exploit code.

Affected packages and fixed versions:
- esaml (Hex): affected all versions; no fix listed
- esaml (Hex): affected all versions up to 4.6.0; no fix listed
- esaml (Hex): affected all versions up to 4.6.0; 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-2026-28809/ (Markdown: https://insights.sbomify.com/CVE-2026-28809/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28809
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28809
- OSV: https://osv.dev/vulnerability/CVE-2026-28809

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28809/
Summaries are generated and may contain mistakes; the official description above is the record.