---
id: CVE-2026-28809
title: >-
  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 messa…
summary: >-
  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 messa…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-611
vendor: arekinath
product: esaml
affected:
  - esaml <= 1.1
  - esaml
  - esaml <= 4.2.0
  - esaml <= 4.6.0
published: '2026-03-23'
updated: '2026-07-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-28809'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-28809.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/Jump-App/esaml/commit/bab85efde7c136911402a881ca55173759467a26
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-28809'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
epss: 0.00281
epssPercentile: 0.20869
ingestedAt: '2026-07-24T15:30:58.244Z'
---

## Overview

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.

## Affected

- `esaml <= 1.1`
- `esaml`
- `esaml <= 4.2.0`
- `esaml <= 4.6.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.